With the continuous development of petrochemical industry, the demand for titanium heat exchanger is increasing year by year in China. Unlike other material heat exchangers, titanium heat exchangers have strict requirements of gas protection when welding heat exchanger tubes and pipe plate joints.Inert gas protection should be applied to molten pools and welds and heat affected zones at temperatures over 400 ℃. In actual production, this intended purpose was achieved by adding a protective gas nozzle to the tungsten electrodes and adding a gas shield for the tube plates. In the whole welding process, gas shield of tube sheet needs to be moved the tube plate gas protection cover constantly based on the welding position.The process is cumbersome and the production efficiency is low.In this paper, Having used ANSYS Workbench numerical simulation software to simulate the temperature field of joint’s welding process and improving the traditional gas protection measures based on the distribution of temperature field.After the actual welding test,This improved gas protective measure worked well and could be applied to actual production.