Abstract: P91 steel, as a new type of martensitic heat-resistant steel, is widely used in the construction of high-temperature and high-pressure equipment in thermal power units and power plant boilers due to its excellent corrosion resistance and high-temperature oxidation resistance. When used in high temperature and high pressure environments, however, P91 steel is prone to damage, leading to performance degradation and even failure. The use of nondestructive testing technology to evaluate the health status of P91 steel can not only effectively ensure engineering safety, but also save economic costs. This article summarized the research achievements of ultrasonic testing, penetration testing, magnetic testing, and acoustic emission testing techniques currently used for quality evaluation of P91 steel. The focus of each nondestructive testing method was summarized, and the problems in the nondestructive testing technology of P91 steel were pointed out. The development direction of these methods was also discussed.