This paper addresses a wireless control system where multiple control loops share spectrum resources and proposes a random access scheme based on imperfect channel state information to achieve control stability. Firstly， in the scenario where multiple control loops access the remote controller with a fixed probability， control stability conditions are derived through the Lyapunov function. Secondly， an optimization problem is formulated with access probability and transmission power as variables， aiming to minimize the total energy consumption of the system while satisfying control stability and transmission power constraints. Since this optimization problem is non-convex and only imperfect channel state information（CSI） can be obtained， a design approach for the access strategy is proposed by combining the Lyapunov stability theorem with mathematical methods such as Bernstein inequality and continuous convex approximation. Simulation results demonstrate that the proposed scheme， compared to existing typical access solutions， can significantly reduce system energy consumption while ensuring control performance.