A fuzzy weighted attitude estimation algorithm is proposed to settle the problem of attitude determination for Optronics Mast Systems (OMS) by combining gyros and inclinometers. Firstly, Euler representation is employed to descript attitude kinematics, and then nonlinear continuum state space model is derived, based on analysis of mathematic model of gyros and inclinometer. Secondly, EKF is used to linear and discrete the models, and a weighted measurement update equation of attitude and gyro drifts is developed under kalman Filter framework. Lastly, according to the relations between the weighted value and body motion, a weighted value determination method is proposed based on fuzzy reasoning system. The experience results show that the accuracy of attitude estimation algorithm is 0.0380. The algorithm also solves the problem of vibration disturber of inclinometer and measure error of gyros in long term.