Abstract: HJ203H is the first horizontal well in Jia'er high pressure sulfurous gas reservoir in Northeast Sichuan Heba block. The well is deep with high corrosion partial pressure, formation leaked easily and kill plugging is very difficult. By analyzing the difficulty of the well test, downhole tools were selected, the production string structure and flow chart were optimized, and process control parameters of main ground test procedure were studied, such as the pulp, fuel injector control and killing, etc. As a result, a test technology of horizontal sulfurous gas wells was created and it has been successfully applied in HJ203H well.