The protective isolation system of oil and gas workplace operation is an important means of isolated protection to operate the oil and gas maintenance of workplace. In this paper, for the ability of the system to exclude combustible gas and welding smoke in the hot work, a large number of conditions were simulated. Analyzed its combustible gas, welding smoke and temperature distribution, summarized the impact of various factors on the performance of the ventilation system, got these parameters such as the allowing leakage of combustible gas, the system for the amount of wind, temperature and operating time allowed to work.. The results showed, isolation protection system using hot work operations can exclude combustible gas produced, welding smoke and heat, and ensure the safety and health of the workers.