Abstract: Aiming at the problem that the existing subcompartment gradient calculation method has poor adaptability to complex terrain and low accuracy of extraction results, a subcompartment automatic extraction algorithm based on DEM was proposed. The accuracy and practicability of the method were tested by comparison with other 2 traditional methods. Results show that the method eliminates the abnormal high and low fluctuation points in the subcompartment, and obtains the oblique plane model of the subcompartment, taking into account the overall situation of the subcompartment. The result obtained by the algorithm is more accurate and practical, and can adapt to the area with high terrain complexity, instead of manually completing the measurement of the subcompartment value, saving time, manpower and material resources.