[en] In order to study the pressure drop characteristics of sump strainer after loss of coolant accident, pressure drop of filter cartridge at full load is experimentally studied and the flow field of collecting tray of sump strainer is simulated by Fluent. The result found that: pressure drop is lager at the part of cross section change, especially in the sudden shrinkage or expansion of cross section; By addition of pressure drop caused by cartridge and collecting tray, which is obtained from experiment and simulation respectively, the total pressure drop of sump strainer meet the requirement of Safety Injection System. (authors)