The helium cryogenic system supplies supercritical helium cooling capacity at 4.5 K for the superconducting magnets in the EAST superconducting tokamak.Four low-temperature helium turbines are used in the 2 kW helium refrigeration system,and their performance and reliability are critical for the continuous operation of the tokamak.The turbines were made by the Helium Mechanics Company in Russia.The start-up process is very unstable,easily broken,and thus testing and improvements are needed.In this paper,we analyze the structure of the helium turbine,make improvements,and describe the testing process and results of the improved helium turbines.Some of the operational experiences during the start-up process and tests are also presented. The helium cryogenic system supplies supercritical helium cooling capacity at 4.5 K for the superconducting magnets in the EAST superconducting tokamak. Flow low-temperature helium turbines are used in the 2 kW helium refrigeration system, and their performance and reliability are critical for the continuous operation of the tokamak.The turbines were made by the Helium Mechanics Company in Russia.The start-up process is very unstable, easily broken, and thus testing and improvements are needed. In this paper, we analyze the structure of the helium turbine, make improvements , and describe the testing process and results of the improved helium turbines. Home of the operational experiences during the start-up process and tests are also presented.