o solve the problem that it is difficult to establish the mathematical model of the system controlled by adaptive discrete-variable structure,an improved model-free adaptive control method based on compact format discrete-time nonlinear system,ICF-MFAC,is proposed.Firstly,the error feedback output control item is added to the CF-MFAC method with only one time-varying integration term,so that the controller can set internal parameters online and thus improve the dynamic performance of the system.Then,the convergence of the ICF-MFAC method is proved by rigorous mathematical derivation.The theoretical analysis indicates that the ICF-MFAC method improves the utilization rate of pseudo-partial derivative estimates and accelerates the response speed of the system.Finally,simulation result of the test on quad-rotor aircraft shows that:compared with the CF-MFAC method,the control error of the improved control method is reduced by 6.12% with no overshoot and small tracking error,while the control effect and robustness are always maintained.