This paper presented the operational principle of formation tester and overview and history of the inflatable packer. The structure and operational principle of packer were analyzed. The setting performance testing instrument was designed. The setting and relieving setting performance of packer was tested with the simulate working environment. The performance of dual inflatable packer was tested in the testing well, The inflation pressure and differential pressure of packer was proved during the testing. The successful application of inflatable packer in formation testing, supplied the significant reference value for the energy exploring and development tools.