The invention provides an edge micro-plasma arc welding forming control method based on telecentric vision sensing and belongs to the technical field of welding quality control. Aiming to solve the problems of unstable welding process and non-uniform weld forming caused by energy parameter fluctuation, heat dissipation condition change and the like in a thin-walled edge joint pulsed micro-plasma arc welding process, the method adopts a monocular coaxial telecentric vision sensing system for acquisition of sharp front transient images of a molten pool, performs real-time adjustment on main arc current pulse modulation parameters on the bases of the front transient images of the molten pool and a mapping relation of multiple electric parameters and mushroom weld forming characteristic parameters in a welding process, and realizes accurate control of the edge micro-plasma arc welding mushroom weld forming. The edge micro-plasma arc welding forming control method can improve the quality reliability of welded products and increase the one-time welding qualification rate, can be applied to an edge micro-plasma arc welding process for thin-walled metal precision components in the fields of aerospace manufacture and the like and is particularly applicable to precision welding occasions for elastic components such as ultra-thin-walled capsules, bellows and the like.