Corporate philanthropy is an important part in exerting the role of the third distribution and promoting common prosper-ity.Why and how corporations engage in philanthropy are two core issues.Starting from the institutionalism theory of organiza-tional analysis,this paper constructed an integrated explanation chain along the logic of"environmental factors→mechanism→corporate philanthropy model",and used a comparative analysis of typical cases to comprehensively compare the similarities and differences of different corporate philanthropy behavior models from five dimensions:philanthropy motivation,action subjects,activity fields,partners and participation means,and reveals their generation mechanisms.This paper found that the corporate philanthropy behavior model is the result of the joint action of the technological environ-ment and the institutional environment.The technical environment and its efficiency mechanism are fundamental forces that affect corporate philanthropy.Meanwhile,corporations are also influenced by regulatory,normative and cognitive mechanisms.The dif-ferent combinations of dominant mechanisms shape the diversity of corporate philanthropy behavior models.Specifically,when the efficiency mechanism works alone,corporations consider conducting philanthropy activities as a more efficient way to achieve strategic objectives,including establishing a good image,repairing corporate reputation in negative e-vents,expanding the market,reducing research and development costs,strengthening employees'loyalty,and increasing the vis-cosity of business partners.These types of corporations select philanthropy activities around business,choose organizations with national organizational systems and pervasive influence to cooperate,and value the strategic functions of philanthropy and volun-tary participation.When regulatory mechanisms play a leading role,corporations try to maintain government relations legally through philan-thropy activities,so that they can avoid government interference,seek political rents,and obtain financing convenience.Through philanthropy activities,corporations can actively comply with official policies and respond to national strategies.These types of companies value the official background of nonprofit organizations and prefer to use administrative strategies to conduct philanthro-py activities and manage volunteering.When the role of normative mechanisms is prominent,corporations aspire to play the role of corporate citizens through phi-lanthropy,giving back to their communities,solving social problems and responding to social needs.These types of corporations choose the field and content of philanthropy activities around social problems they care about,tend to cooperate with grassroots nonprofit institutions that are highly compatible with their philanthropy missions and are willing to cultivate nonprofit institutions'programs and promote the infrastructure construction of the philanthropy sector.When the role of cognitive mechanisms becomes prominent,corporations try to undertake the cultural mission reasonably through philanthropy,including following the guidance of values,responding to cultural expectations,practicing traditional no-tions,and shouldering the expected social responsibilities.The philanthropy direction and financial investment of these types of corporations are strongly influenced by entrepreneurs'personal values.The traditional cultural characteristics in philanthropy ac-tivities and voluntary participation are relatively strong.The main policy implications of this paper are that corporations of different natures and industries are dominated by different environments and mechanisms to shape their philanthropy behaviors.Specifically,state-owned enterprises are more affected by the regulatory mechanism,while private enterprises are relatively more exposed to the cognitive mechanism.C-end enterprises are more influenced by the efficiency mechanism,while B-end enterprises are more influenced by the normative mechanism.Our findings suggest that the government should accurately find the core shaping force of corporations'philanthropy behaviors,pay more attention to the stability and sustainability of donations,and be more sensitive to the preferences and characteristics of corporate voluntary participation.Based on that,the government can mobilize resources accurately and guide more corporations to engage in philanthropy and the third distribution.Under this,nonprofit organizations can also more effectively develop and main-tain corporate donors.