The aim of this paper is to provide a new suitable method for smart grid state estimation. Based on the non-linearity of methods used to solve the state estimation problem, in addition to the ability to solve such issues, it is also necessary to be responsive and have acceptable accuracy. In this article, a new metrology of optimization, Bat Algorithm (BA), based on the Weighted Least Square (WLS) method is presented. This algorithm is equipped with a new self-adaptive learning that improves the performance of BA and has a better effect on optimization. Bat algorithm can estimate voltage and angle output values by weighted least square method. The advantages of this method are lower cost function, faster solution and globally-locally better search in comparison with other algorithms. 5 6 7 8 9 10 11