Based on data from Chinese indus-trial enterprises from 1998 to 2007,this paper em-ploys an instrumental variable approach to examine the heterogeneity of FDI horizontal spillover effects on domestic firms'TFP,considering the differences in production technology and local endowment struc-tures.The study further explores the underlying causes of this heterogeneity through the channels of knowledge spillover and competitive effects.The findings indicate that FDI generally has a negative impact on domestic firms,with an increase in foreign investment within the industry leading to a decline in TFP.Firms with production technologies less aligned with local endowment structures experience more significant negative effects from FDI,resulting in larger decreases in TFP.Among the two channels,firms less aligned with endowment structures benefit less from FDI knowledge spillovers and are more susceptible to competitive pressures from FDI.