According to the quality evaluation requirements of high temperature medium mechanical seal in petrochemical industry,the performance test device and system of high temperature medium mechanical seal were developed.The test device was designed with main shaft cantilever and seal chamber independent double support,which has simple structure and is convenient for seal installation.The high temperature medium in the system adopted forced circulation,the maximum operating temperature is 400 ℃,and the temperature is stabilized by precise control.Through theoretical analysis and operation test,it is shown that the device and system designed are safe and reliable,and stable in the operation process,which can fully meet the high temperature test requirements of relevant standards and evaluation specifications of mechanical seal,and provide test equipment support for high temperature medium mechanical seal product development.