Parameter sensitivity analysis of nuclear reactor passive system is the main part of uncertainty analysis for passive system reliability. There are drawbacks for correlation coefficient to describe the parameter sensitivity of success criteria of passive system physical progress. So an iterative method was proposed, the method took account of correlation coefficient and partial correlation coefficient for input parameters, success criteria and correlation coefficient between parameters comprehensively, and the validity and practicability of the method were verified by a specific case. It is suitable for iterative method to analyze partial correlation of success criteria, to recognize more accurate sensitivity parameters and to provide reference for improving reliability of passive system physical process.