As a high-performance flexibility coupling, nonlinear grid coupling has been used widely in many fields, such as aerospace, aviation, metallurgy for instance compressor system and so on. Over a long period of fatigue operation, its structure parameters will change a lot. The system is apt to go chaos, which results in the whole system instability. According to reliability theory and adaptive control theory, an adaptive control model of nonlinear grid coupling is built in this paper, and a novel parametric adaptive algorithm is presented. In addition, combining with an instance some numerical simulation analyses are performed. The reliability of chaotic system of nonlinear grid coupling is calculated, and some comparisons with the reliability that in normal state are provided. Calculation and analysis results show that the parametric adaptive control method possesses strong capability of stability in control, and the working state can be adjusted to normal timely. Consequently, the reliability of controlled system increases remarkably compared with the reliability of chaotic system. The method opens up a new way for reliability design of mechanical system, and provides a way to monitor the security of the whole system dynamically.