Abstract: One safety improvement considering Fukushima accident is proposed for Qinshan Nuclear Power Plant unit-1. Under the sever accident condition, the reactor residual heat of the reactor core is removed by supplying the emergency water to the primary and secondary loop with the mobile pump, and add water supply channel, interface, water resource and mobile pump. The effect of added facilities on the safety of normal operation is analyzed. The potential safety problem resulted from the emergency water supply is discussed, and the improvement or mitigation measures is proposed.