In this paper, Attitude Determination and Parameter Identification problem of a LEO satellite are studied. In Attitude Determination System three rate gyroscopes, three axis magnetometer and a sun sensor data are used. Using Kalman Filter algorithms angular rates and quaternions are estimated. In these algorithms, rate gyroscope bias measurements are also taken into consideration in state estimation. In Parameter Identification part, the Moment of Inertia values of the satellite are estimated by using Least Square Estimation method. Finally by combining these two parts, the Attitude and Mol values of the spacecraft are obtained.