Abstract: The energy consumption of the test and control system in automatic vertical drilling tools is provided by the downhole turbine generator. In order to make downhole turbine generator adapt to mud working condition, we combined the dynamic sealing compensation protection technology with the magnetic driving technology, and achieved good results in improving the dynamic sealing reliability, increasing the service life of high speed bearings, improving generator efficiency, and avoiding the generator coil and the magnet steel from being eroded by mud. The design of this turbine generator covers not only the design of the performance and structure parameter of the generator itself, but also the related parameter design of the magnetic driver and the compensation spring, one of the dynamic sealing compensation protection components. The paper gives a design method for the magnetic driver of downhole turbine generator, and discusses the spring design of the dynamic sealing compensation protector.