Abstract: It is for the first time that the transient characteristic test on PRHRS has been performed for Chinese advanced PWR. A total of 78 sets of test data at transient state have been obtained, and the transition characteristics of cold startup, warm startup, startup without the emergency feedwater, water hammer, and pressure peak value were investigated. Subcooled water of EFWT and the air-cooler can slow down the pressure rise effectively while blackout accident occurs. There is no remarkable difference on transition characteristics between cold start-up and warm startup. The main influence factors, for example, feedwater velocity, feedwater temperature, feedwater position, and various position of air cooler on the water hammer were identified, but if feedwater temperature is higher than 52℃ or the resistance of feed water loop is large enough, no water hammer is observed. Transient characteristic research shows that the cold startup and warm startup of the PRHRS have better transition characteristics, and have the capability of removing the core decay residual heat safely.