The utility model discloses an internal test plate for testing the performance of a photoelectric module in a high-temperature environment. The internal test plate comprises n SFP sockets. N is a natural number greater than one; the n SFP are simultaneously connected with an I<2>C bus multiplexer and a simulation multiplexer respectively; the I<2>C bus multiplexer and the simulation multiplexer are connected with a digital signal processor; the output end of the digital signal processor is connected with a level conversion chip; and the output end of the level conversion chip is connected with a host computer. In the prior art, an LED is separated for individual testing, however, according to the utility model, the photoelectric module is directly tested so that the problem that the service life of the LED is equivalent to the service life of the photoelectric module is generally prevented, and the service life of the photoelectric module is more real and reliable.