Abstract: The cloud control system with energy constraint is considered. The stochastic disturbance is added to only a partial of channels to protect privacy. Mutual information is used as the privacy measurement of the system. An optimization problem is constructed to describe the system targets with the estimation performance loss caused by the stochastic disturbance as the constraints. To get the optimal privacy mechanism, the optimization problem is transformed to a convex optimization problem and a 0-1 programming problem. The optimal variance of the disturbance adding and the privacy addition and scheduling policy can be obtained respectively by solving the above two problems. The effectiveness of the optimal privacy protection mechanism is verified by the numerical simulation.