The thunderstorm identification algorithm of radar data is an important part of the thunderstorm tracking technique. The traditional continuous region method can only adjust thunderstorm identification results by changing the reflectivity threshold, which cannot meet the current application requirements. This paper proposes a storm identification method based on the OPTICS (Ordering Points to Identify the Clustering Structure) algorithm. This method can identify storm cells based on the density information of points with high reflectivity. Using volume scan data of high-resolution X-band weather radar in two thunderstorms, the performance of the proposed algorithm is tested and compared with the traditional method. The results show that this method can overcome the problems that may occur in traditional methods in high-resolution radar data, such as being unable to distinguish adjacent cells or getting too scattered identification results. Besides, it can flexibly adjust the output results without changing the reflectivity threshold to meet the needs of different applications.