Bridge load testing analysis system software BLT was developed for bridge detection test analysis. It could establish a three-dimensional finite element model of bridge based on solid element or Beam element, to make the static and dynamic test analysis, calculate the test load efficiency, and investigate the theoretical calculations of stress and displacement in the location of the measurement points. This system is a useful auxiliary tool for bridge detection, and also can analyze the spatial force state of the wide, curved, cable-stayed bridges. This paper details the characteristics of the overall concept of the system, the calculation principle as well as the real bridge application examples.