In this paperthe control method of light panel auto-dimming in cockpit is studiedand a sliding mode control method for auto-dimming system is proposedthe design of control systemmodeling of controlled object and construction of sliding mode controller are completed.By using Matlabthe control rate is simulatedcomparing the system step response as well as the tracking accuracy with different parametersand optimizing the controller parameters.The results show that the control system has a fast response rategood tracking accuracyand can adjust the power consumption of light panel according to the change of the illumination of ambient lightthus achieving the control objectives of stabilizing the character contrastreducing the power consumption of light paneland improving the crews work performance.