The method for calculating of the temperature when surfacing of complex-shaped workpiece by solving non-stationary and nonlinear equation of thermal conductivity in heterogeneous layer, which allows taking into account the elements of the clamping device and not describing numerous boundary conditions is presented. Example for calculating of the heating temperature of spherical plug of the ball valve during surfacing on spherical surface via welding deposition with spiral and back-and-forth movement of the heat source is given. The calculated temperature variation in the base material during the surfacing of specific workpieces makes it possible to develop program for adjusting of the surfacing mode to ensure the stability of the dimensions and properties of the deposited layer.