For the strength design of the brake system of a forklift truck, a procedure to calculate the internal forces acting on the system is presented in this paper. Vehicle dynamics, brake system kinematics, and internal force equilibrium analysis are integrated into the procedure. Design parameters such as stopping distance, maximum decceleration, and maximum torque generated by pedal force are considered in the vehicle dynamics, and geometric parameters of the brake system are considered in the brake system kinematics. With the two analysis results obtained, the internal forces acting in the brake system are finally calculated in the procedure.