In order to understand the traffic safety characteristics of two-lane highways in China's Mountain area , a systemic analysis was conducted. Two-lane Highways with more than 3,500 kilometers were investigated for accident data, geometry designs and roadside features. The analysis includes a routine analysis, single-factor safety analysis and multi-factor safety analysis. The routine analysis shows that segments passing by villages have a greater tendency to be involved in traffic accidents. The single-factor analysis shows that two-lane highways with driveway density of 5 and roadbed width of 8 metersexperience the lowest accident rate with respect to other analyses. Negative binomial modeling technique was applied and proven to be the best for multi-factor analysis. The results show that village influence, truck proportion, the horizontal alignment, and driveway density influence two-lane highway safety significantly. Two-lane highways, such as secondary, tertiary and some of fourth grade highways, are main kinds of highways in China's mountain areas. The secondary and tertiary highways have less than 20 percent of total highways, but there were more than 60 percent of the total traffic accidents and death counts in 2007[1] in those locations. Traffic safety conditions of two-lane highways is very serious subject. Because most two-lane highways are located in mountain areas have many fatal accidents , it is necessary to study the traffic safety problem of the two-lane highways in mountain areas. Usually, two-lane highways have less roadbed width(including the width of road surface and shoulder) and few driveways(access roads) in mountain areas than in plain areas. The factors which influence traffic safety are also different, but roadbed width, driveway, truck transportation and inappropriate geometric alignment are the most important factors that influenc traffic safety in mountain areas. To understand the safety features of two-lane highway in China's mountain areas, research on two-lane highways in Beijing have been conducted. The research included routine analysis, single-factor safety analysis and multi-factor safety analysis aiming at those specific factors listed above. The routine analysis does not only to show some basic safety characteristics of two-lane highways, but also is the basis for the multi-factor analysis. The single-factor analysis shows the valuable safety characteristics respectively and can be one part of the accident prediction model. The multi-factor analysis shows the safety characteristics when putting many variables together.