In this study, weighted least square method (WLSM) is used for attitude determination of nanosatellite. To apply the WLSM, three different vectors are used. These vectors are; Earth's Magnetic Field vector, Sun vector and Nadir vector. Using these vectors, three different vector pairs are obtained and with these pairs three algorithms are examined; (1) Earth's Magnetic Field vector and Sun vector, (2) Sun vector and Nadir vector, (3) Earth's Magnetic Field vector and Nadir vector. In simulations the actual values of Euler angles are compared with obtained angles via WLSM and the error rate is investigated. This process is done for all the three algorithm and the results are shown in graphic using MATLAB program. According to the results, these three algorithm are compared and the algorithm and the vector pair is determined which gives the most accurate results.