This article discusses the multi-criteria parameterization of the crank-slider group of the Stirling engine type "alpha". The dependences of the displacement of the piston and the displacer are obtained, taking into account a number of variable geometric parameters. The resulting equation of movement of the piston from displacement of the propellant is composed of a crankshaft angle, which will allow to obtain a numerical model simulation of the crank-slider group that will significantly reduce the time of numerical calculations. The dependence of the torque on the crankshaft with known pressures on the piston and the displacer is obtained. This study will eventually allow us to determine the optimal parameters of the designed steering engine, depending on the power and operating temperatures. This will allow us to design an engine for use in the timber industry (use of logging and woodworking waste as fuel). Effective use for energy generation is an urgent task of the forest complex. Currently, obtained torque equation will allow us to study the working process of the engine when solving the gas-dynamic problem of cyclic flow of gas from the cavity of the piston cylinder to the cavity of the displacer cylinder and back.