The invention discloses an intelligent inspection system and method in a thermal power plant. The system comprises a wireless industrial Ethernet network, an inspection data center and a multifunctional inspection terminal, wherein the inspection data center and the multifunctional inspection terminal are in wireless connection with the wireless industrial Ethernet network; the inspection data center is connected with a DCS (Distributed Control System) and SIS (Safety Instrumented System) of the power plant, has synchronous clock periods and is capable of inquiring, reading and writing real-time and historic databases of the DCS and the SIS of the power plant; the inspection data center drives the multifunctional inspection terminal to sample data of an inspection target via the wireless industrial Ethernet network and exchanges data with the multifunctional inspection terminal. The invention further provides the inspection method of the system. According to the method, the clock of the DCS system of the power plant is synchronized via wireless communication, various diagnosis signals are conveniently collected by using the multifunctional inspection terminal and are integrated with original DCS data, and trend analysis and evaluation are carried out on inspection data under similar working conditions so as to prompt inspectors to master running states of equipment and parts and maintain and preserve the equipment and the parts in time, so that the equipment maintenance level and the running safety and reliability of the system are increased.