Abstract: In the actual production, most angle welding is asymmetric, causing the instable back penetration and the poor forming quality. The temperature field and molten pool forming were studied in order to optimize the selection of welding parameters and improve the forming quality. The three-dimensional mathematical model of low carbon asymmetric angle filler wire TIG welding has been developed to calculate, considering with the effect of temperature, radiation and convection heat latent on physical properties of the material. Compared to discuss the effect of welding current on temperature field under the different structure, focus on analyzed the effect of the parameters on the asymmetrical angle welding penetration. The results show that the asymmetric fillet weld temperature distribution is not uniform, and back weld width which changes on the current is very sensitive, the influence of welding current on weld pool shape is significant. Through the three group experiments, the weld heat affected zones are received, its shape and size agree well with the simulation results, which verifies the validity of the the oretical analysis.