The invention discloses a tight combination navigation method based on robust SCKF (Square root Cubature Kalman filter). The method comprises the following steps: sequentially simulating to generate IMU (Inertial Measurement Unit) data and a GPS (Global Positioning System) intermediate-frequency signal of a guided missile through a track generator and a satellite signal simulator; carrying out inertial navigation calculation on the IMU data generated by simulation; injecting the GPS intermediate-frequency signal into a software receiver and carrying out navigation calculation; establishing a GPS/SINS (Strap down Inertial Navigation System) tight combination navigation system model under a launch inertial coordinate system; on the basis of standard square root cubature Kalman filter (SCKF), introducing steady M estimation and carrying out self-adaptive adjustment on a measurement noise array of the system, so as to construct a robust square root cubature Kalman filter (RSCKF) algorithm; carrying out filtering correction on a system state. According to the tight combination navigation method provided by the invention, measurement unusual errors in the system can be effectively eliminated, and an anti-interference capability and navigation precision of GPS/SINS tight combination navigation are improved.