To realize the pin by pin calculation function of the sub-channel analysis code LINDEN and improve the accuracy of core thermal hydraulic analysis by LINDEN code,an automatic modeling function has been developed for the full core pin-by-pin calculation,and the storage and solution problems of large sparse matrices have been solved.The full core pin-by-pin calculation and analysis of 157 assemblies were carried out.The calculation results indicate that LINDEN can perform full core pin-by-pin calculations,and the detailed distribution results of key thermal hydraulic parameters such as coolant temperature distribution,DNBR,mass flow rate distribution can be obtained.The power difference between adjacent assemblies affects the distribution of thermal hydraulic parameters within the assembly.