This paper introduces a new approach to solve the problem of power system state estimation and check the observability of the measurement scheme. The state estimation is a powerful technique for system monitoring and control. Through a numerical method for observability analysis in power system state estimation based on weighted least square (WLS), the system state will be implemented and the measurement scheme will be judged. In addition to that, investigation for the effects of the measurements redundancy on the accuracy of the estimated variables is also discussed. The technique is applied to IEEE 30 bus system. Test results show the effectiveness of the proposed method to reach the best of the state estimator solution.