A solid small rocket torque loading process seal ring compression amount online detection method is characterized in that by analyzing the stress conditions of the screw threads, a spring washer and a seal ring during a process of loading a solid small rocket on an automatic loading device, the relation between the stresses of the screw threads, the spring washer and the seal ring and the screwing torques during the loading process is obtained; the loading process is divided into four stages, and a torque-angle ideal curve during the loading process is drawn; and by analyzing the slope of each stage curve of the ideal curve, an angle value when the position of the seal ring starts to be contacted during the loading process is obtained, thereby calculating the compression amount of the seal ring. By the method, the compression amount of the seal ring can be obtained without needing to measure, mark and calculate the solid small rocket again, the labor intensity is reduced, a measurement error brought by repeated measurement is avoided, and the online real-time accurate measurement of the compression amount of the miniature solid rocket seal ring is realized. The method can be used as the determination basis of the solid small rocket screwing degree detection.