The invention provides an urban trunk road vehicle trajectory reconstruction method based on fixed-point detector and signal timing data fusion. The method comprises the following steps: 1) establishing a basis matrix: determining a road occupation condition matrix Point[n, distance, t] at the t moment according to a vehicle running matrix Car [vehicle, t] at the t time, and then, calculating vehicle most probable running status at the t+t0 moment according to the road occupation condition matrix Point[n, distance, t], and thus a Car [vehicle, t+t0<->] constant iterative process is generated; 2) carrying out vehicle generating; 3) carrying out vehicle behavior decision; and 4) judging whether trajectory reconstruction is finished. The method has the advantages of fusing fixed-point detector and signal timing data, not depending on high-quality floating car data and demanding less on traffic data acquisition environment. The method is suitable for multilane and coming/going vehicle traffic interference cases, is wide in applicability, is complete and comprehensive in reconstructed trajectory, and can realize the functions of environment assessment, signal control coordination, travel time estimation and jam state early warning and the like.