In order to expound the impact of traffic condition to road injury, the relations of road injury with motorization, road situation e and highway capacity were studied, using Canonical Correlation analysis method. Results showed that the Canonical Correlation Coefficient A(0.9486) was representing the direct correlation of the motorization with the injury and death rates, referring the higher the motorization, the greater the death and injury rates. The Canonical Correlation Coefficient B(0.9220) indicated the direct correlation between the highway capacity and the frequency of road injury, as well as the larger the highway capacity, the more frequency of road injury occurrance. The Canonical Correlation Coefficient C(0.6446) revealed the relations between levels of road situation and the accident rates per 10,000 vehicles. Results showed that the higher the quality of roadway, the lower was the accident rate. In view of this, traffic condition was closely related to road injury. Thus, the frequency of accident, death rate and injury rate could be reduced through improving the road quality and traffic conditions. Relations between two sets of random variables, the ties of the canonical variables and the original variables could all be well analysed with Canonical Correlation analysis. Canonical Correlation is useful to analyse two sets of random variables in epidemiological studies since it provides a great amount of information to be applied and operated widely and easily.