Abstract: Kinetic equations of multibody systems with scleronomic constraints are projected along the feasible and unfeasible directons of the constiaints respectively,and generalized accelerations of the systems are decomposed along the two directons using the bases of constraint matrix and its orthocomplement.Pure differential equations of the systems and formulae to solve the constrained forces are thus obtained.A method to correct violation of constraints is simultaneously advanced. Finally, an illustrative example is presented.