The invention discloses a control method for asymmetrical fillet weld joint melting form and melting depth. Melting forming of an asymmetrical fillet weld joint is controlled by adjusting the weldinggun angle, a front melting pool model is identified on the basis of a vision method, melting depth estimation and control are achieved, and due to the fact that the heat dissipation difference of twoside plates of an asymmetrical structure is large, melting forming of the two sides is difficult to control. The control method comprises the steps that on one hand, the melting pool form is controlled by controlling the welding gun angle, on the other hand, a finite-size fillet weld joint workpiece temperature field analytical model is derived on the basis of an instantaneous point heat source temperature field analytical equation of an infinite-body green function and a heat source equivalent method, melting pool edge feature points are obtained by means of image treatment to correct the analytical model, numerical calculation is conducted through the corrected analytical model, the maximum coordinate of the melting point temperature in the depth direction is solved, and then melting depth calculating and solving can be achieved. Through the method, control over melting forming of the asymmetrical fillet weld joint can be achieved, and the purpose of improving the welding quality ofthe special structure is achieved.