The invention discloses a testing system and testing method for testing or detecting the discharging capacity of a safety valve of a voltage-stablizer. The testing system comprises a steam supplying system which is connected with a temperature reduction and pressure reduction system, the temperature reduction and pressure reduction system is connected with a voltage stabilization system, and the voltage stabilization system is connected with a measuring system and the safety valve of the voltage-stablizer. According to the technical scheme disclosed in the invention is adopted, the testing system and testing method can be used to test or detect the discharging capacity of the safety valve of the voltage-stablizer, and accurately obtain discharging capacity characteristics of the safety valve, thereby providing basis for design improvement and engineering application of the safety valve of the voltage-stablizer, meeting the requirements of a nuclear power plant, and ensuring operation safety of the nuclear power plant. The system flow and equipment are simplified, so that the system construction period is short, and the operation is simple. The measurement accuracy is greatly improved, and the system construction and operation cost is reduced, thereby sharpening the competitive edges.