Abstract: The weld bead forming geometry of tungsten inert gas welding (TIG welding) directly affects the evolution of the heat affected zone and service reliability of tempering weld bead repair. To meet the engineering requirements of "rapid parameter selection, minimal testing, and interpretability" in the repair of tempering welds in nuclear power equipment, this paper takes automatic wire filling TIG single pass welding as the object and adopts the technical route of "pre testing to determine parameter range - parameter combination testing to obtain data - multiple linear regression modeling - independent parameter verification" to study the relationship between arc voltage and welding current, tungsten electrode to workpiece distance, as well as the coupling effects of welding current, welding speed, and wire feeding speed on weld bead width, depth, and clearance. Under the condition of controlling the distance between the tungsten electrode and the workpiece to be constant, regression expressions for three types of geometric dimensions were established, and the applicability of the model was evaluated through variance analysis and coefficient of determination. The results show that within the process window set in this article, the arc voltage is more sensitive to the distance between the tungsten electrode and the workpiece, and the influence of current changes on voltage is relatively weak; In the geometry of weld bead, welding speed and welding current play a crucial role in the fusion depth and width to depth ratio, while wire feeding speed has a more significant impact on the control of excess height. Based on regression models, it is possible to solve the inverse parameters of target melt width, melt depth, and excess height, which can be used for rapid development and first round optimization of tempering welding process.