In tillage operations to know soil reaction force on the tools working inside soil and under agricultural vehicle tires, soil mechanical parameters should be determined. Measurement and determination of soil mechanical parameters will be helpful for optimum designing of tillage tools to decrease required energy. An experimental device was developed at the University of Mohaghegh Ardabil which is able to conduct three soil mechanics tests of sinkage, penetration and shear, by which soil cohesion, internal friction, stiffness, soil constant and strength were determined. For sinkage and penetration tests an electromotor power was translated to a rectangle plate via a translating system such that moves plate or cone penetrometer vertically and forces it in soil. While fore shear test it moves shear plate horizontally as plate shears the soil. Required forces for sinkage, penetration and shearing were measured by loadcell and vertical and horizontal displacements were measure using linear potentiometer (LVDT). All data logged to a loptop via a data logger. All mentioned parameters for a type of soil were computed desirably related tests.