According to the survey report released by the WHO in October 2015，about 1.25 million people died in traffic accidents in the world each year. Traffic accidents have become the main reason for the 15 to 29 years old young man’s death. 90% of the world’s road deaths occur in low and middle income countries，but the number of vehicles in use in these countries only accounts for no more than 50% of total vehicles in use in the world. With the rising proportion of the economy in developing countries，the global car ownership has increased rapidly. As of 2015，the total vehicles in use in the world have reached 1.1 billion units. But the development of the transportation infrastructure and traffic safety and management level have not kept pace with the speed of economic development in undeveloped and developing countries. The number of road traffic accidents and the severities both tend to be more serious. Although the many new technologies have reduced traffic accidents and traffic injuries，but active prevention is still the main method to prevent and reduce road accidents. In order to prevent road accidents，we should have in-depth understanding of road traffic accidents. So for traffic safety researchers，they should make extensive investigations to collect traffic accident information，conduct in-depth analysis of the characteristics of road traffic accidents，research the internal mechanism of the road traffic accidents，and look for the factors influencing road traffic accidents. All these are the most important tasks at present.