Abstract: Lead cooled fast reactor has obvious advantages in fuel proliferation and nuclear waste treatment. For the Europe Lead-cooled System (ELSY), based on the “two-step method”, Monte Carlo software is used to generate few group component parameters, and after section correction, it is passed to the determining theory program MORPHY for core calculation. The effects of section modification and angle development order on the calculation accuracy were analyzed, and the effective multiplication factor, normalized flux level and control rod value of the ELSY core were quantified and compared. For different examples, transport correction and neutron multiplication effect correction were adopted, and the core calculation was developed with S₄ order. The maximum deviation of effective multiplication factor was 38×10⁻⁵, the calculation deviation of control rod value was within 45×10⁻⁵, the maximum absolute deviation of normalized neutron flux density was 9.73%, and the average absolute deviation was less than 2%. The feasibility of MORPHY program in the physical analysis of lead-cooled fast reactor is preliminarily verified, which is of reference significance for the subsequent development and use of the program.