The lightning monitoring and location are of great significance to reduce the lightning disaster, and the location accuracy is the key index of the lightning location system. Aiming at the problem that the positioning accuracy of traditional positioning methods is greatly affected by gross error of data and station network layout, a positioning method based on time difference and clustering algorithm is proposed. The lightning positioning data is combined based on the principle of time difference of arrival, K-means clustering algorithm is used to classify the combined positioning values and remove outliers to obtain the final accurate positioning value. Taking the lightning detection network in Jiangsu Province as an example, the numerical distribution of location error, the time measurement accuracy and the influence of station network layout on the location error are quantitatively studied. The results show that compared with the traditional arrival time difference method, the regional positioning error calculated by this method is reduced from 5 km to 2 km; The root mean square error of four station positioning is reduced from 0. 89 km to 0. 07 km; The location error is slowly increased due to the sharp increase of the time measurement error, and the impact of website layout on the location error is significantly reduced.