The operation safety and efficiency of high-speed railway have been widely concerned. Due to the joint influence of environment, equipment, personnel and other factors, accidents are inevitable in operation process. However, few studies focused on identifying contributing factors affecting severity of high-speed railway accidents because of the difficulty in obtaining field data. This study aims to investigate the impact of factors affecting severity of general high-speed railway. 14 potential factors were examined from 475 data. The severity level was categorized into 4 levels by delay time and the number of subsequent trains that are affected by the accident. The partial proportional odds model was constructed to relax the constraint of parallel line assumption. The results show that 10 factors are found to significantly affect accident severity. Moreover, the factors including Automation Train Protection (ATP) system fault, platform screen door and train door fault, traction converter fault, and railway clearance intrusion by objects have an effect on reducing the severity level. On the contrary, the accidents caused by objects hanging on catenary, pantograph fault, passenger misconducting or sudden illness, personnel intrusion of railway clearance, driving on heavy rain or snow, and train collision against objects tend to be more severe. Keywords: High-speed railway, Operation safety, Accident severity, Partial proportional odds model

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