With vehicle technologies development，vehicle safety is much better than before, many companies put research focus on harder accident scenarios. 25% overlapping rate collision is considered as one type of most dangerous collision，this paper study this type accidents base on China In-Depth Accident Study (CIDAS) database. this database include more than 4000 cases in China. We study the accident contents from impact characteristics, human injury, seat position, injury causing part,and dirver behaviours. the paper can help researcher to create scenarios to test the ADAS technology in China and promote ADAS system.