Aiming at the cyber physical system (CPS) under false data injection (FDI) attack, a control method based on sliding mode and extended observer is studied. Firstly, the system is dynamically linearized, an extended observer is constructed, and the convergence condition of the observation error is analyzed. Secondly, the integral sliding mode surface is designed, the asymptotic stability criterion of the sliding mode system is derived by using linear matrix inequality, and the sliding mode vector satisfying the gain performance of the system is obtained. Then, based on the exponential reaching law, an adaptive integral sliding mode controller is proposed to eliminate quantization errors and generalized disturbances, so that the system can reach the sliding surface. The advantages of this method are high estimation accuracy, fast response speed, and strong robustness to FDI attack and quantization parameter mismatch. Finally, numerical simulation verifies the effectiveness of the method.