Abstract: A mathematical model of static force transmission for the Delta parallel mechanism is established by using vector mechanics and virtual work principle. The gravity compensation torque of kinetic parts is analyzed through model simulation. The concept of force transmission capacity is proposed,the relation between force transmission capability and condition number of the force Jacobian matrix in operation position is discussed,and distribution of force transmission capacity is analyzed initially in a given workspace. Results obtained and force transmission index proposed can be applied to optimizing force transmission performance of the Delta mechanism and other mechanisms.