This invention relates to a kind of attitude definition method of micro inertia mixed navigation system of microminiature aero craft, belongs to microminiature vehicle attitude definition method. The method utilize guidance information, control Kalman filter noise matrices, to realize self-adapting adjust according to flight status; through parameter adjust to realize attitude definition of micro inertia mixed navigation system on dynamic airborne conditions; the specific process: through GNC closed loop circuit guidance algorithm, to gain aero craft barrel angle; through sensor picking, obtain vehicle rate and specific force; by strap inertial navigation algorithm to resolve out vehicle attitude, velocity and position information; by accelerometer and GPS data to count pose and position measurement information of aero craft; real-time compute horizontal attitude variance of Kalman filter observation noise matrices, through Kalman filter to estimate error of strap inertial guidance system; Amend above acquired pose, velocity and position information, and took as feedback information to import in control system.