Abstract: Highway steel bridge ultrasonic detection sensitivity standard being completely imitating the railway steel bridge ultrasonic testing standard, but the highway bridge load is very different from that of the railway bridge load. Therefore, copying the railway steel bridges ultrasonic testing standard exactly may produce large error. In this paper, by comparing the highway bridge load and railway bridge load, the respective percentage of the live load in the total load was obtained. By the analysis of the ultrasonic testing standard optimization coefficient, especially under the highway bridge load of grade Ⅰ and Ⅱ, a suitable ultrasonic testing DAC curve for highway steel bridge under the highway bridge load of grade Ⅰ and Ⅱ was finally worked out.