China New Generation Radar use radial and tangential velocity gradient or the result of the combined based on fixed scale to detect wind shear.These methods are easy to cause omission.Aiming at this problem, a new low-level wind shear alerting algorithm based on adaptive scale is presented in this paper. The core idea of the algorithm is to calculate the velocity gradient based on several adaptive scales.Firstly, select multiple scale to calculate maximum wind shear intensity factor,choose the scale corresponding to the larger intensity factor value as the adaptive scale . Secondly，do the least squares fitting for many times on the radial. Finally, compare the fitting gradient with provisions of international low-level wind shear threshold and merger them to come to the conclusion. The performance of the proposed method is verified through the real data from The Northeast Flugsicherung, the results show that the proposed algorithm can detecte wind shear of all kinds of scales. Therefore, the proposed method improved the alarm rate. It has a certain practical application value.