This paper introduces a new kind of train impact detecting system that detect the train impact through detecting the train running acceleration,proposes that uniting the train running acceleration and the change rate of acceleration to token the train impact. The detector takes the portable computer as platform of data processing,utilizes the database technology to process data,making instrument Pc true,and improving the data processing ability of the instrument. The detector can show the train running acceleration on-line and real-timely,indicating the train impact situation directly,and uses the method that the software and hardware unifies to strengthen the system anti-jamming ability. At present,this detector has been tryout in some locomotive depots,each design function and the performance index conforms to request of the scene; the anti-jamming ability is strong,the monitor precision is reasonable,the detector can carry out the on-line examination to the train impact and monitoring the train running condition. This paper introduces a new kind of train impact detecting system that detect the train impact through detecting the train running acceleration, ie that uniting the train running acceleration and the change rate of acceleration to token the train impact. The detector takes the portable computer as platform of data processing, utilizes the database technology to process data, making instrument Pc true, and improving the data processing ability of the instrument. The detector can show the train running acceleration on-line and real-timely, indicating the train impact situation directly, and uses the method that the software and hardware unifies to strengthen the system anti-jamming ability. At present, this detector has been tryout in some locomotive depots, each design function and the performance index conforms to request of the scene; the anti-jamming the monitor can carry out the on-line examination to the train impact and monitori ng the train running condition.