The present invention relates to a test device of a self oil circulating pump and oil mechanical seal performances for a nuclear main pump. Two performance test results are obtained at the same time.The structure design is compact, the concept is creative and advanced, the test data is real and reliable, the cost is saved, the economic performance is enhanced, and a solid foundation is laid for the nuclear main pump design domestication and application of products to real machine operation. A self oil circulating pump impeller 27, an oil guide vane 28 and an oil mechanical seal module 29 aredriven by a first belt pulley 21 and a second belt pulley 24 with a speed increasing ratio of 1.03471:1 to obtain a rotation speed of 1490r/min being the same as that of the real machine, an oil pathcontrol system is employed to obtain technical data such as pressure and flow of lubricating oil of the self oil circulating pump impeller 27 and the oil guide vane 28 to determine the structure and the size of the impeller 27, and the test also verifies the seal performance of the sample machine of the oil mechanical seal module 29.