Abstract: There is a great difference between the calculated collapse under overburden pressure and the measured collapse，it is one of the main reasons for the difference that the method indoor for determining coefficient of collapsibility under overburden pressure has theory deficiency，it has become an urgent requirement how to correctly evaluate loess foundation improving the theory and method for determining coefficient of collapsibility under overburden pressure． An improved method for determining coefficient of collapsibility under overburden pressure was established in the literature No. 10，based on which taking dry density，moisture content，interparticle force and natural weight pressure as factors，the problems of determining coefficient of collapsibility under overburden earth pressure were studied by experiment． The rationality of the improved method was analyzed，and the influencing rule of each factor on the difference between the two determination results was explored by comparison of Rc and 0 ，Rc was the ratio of coefficient of collapsibility under overburden pressure determined by the improved method and current method，0 was the correction coefficient varied with the soil．Research showed that the overburden pressure，dry density，water content and interpartical force had different effects on Rc ，dry density was the most important factor， water content and overberden pressure were the less ones，and the interpartical force was the minimum． The improved method had general applicability and theoretic rationality，which could reduce the effects of soil disturbance on coefficient of self-weight collapsibility．