Wheelset geometric parameters, such as the flange height and wheel diameter, are of great significance for detection to ensure the operational safety of trains. In this article, an efficient measurement method is presented to achieve the dynamic and noncontact measurement of wheelset geometric parameters using 2-D laser displacement sensors (LDSs). The mathematical model of the measurement system is established to calculate the wheelset geometric parameters. A standard calibration mechanism is specially designed to calibrate the rotation matrix, horizontal angle, and coordinate origin distance of different sensors. The tread profile mapping method is investigated to decide the feasible scanning range. The error caused by laser dislocation is analyzed, which shows that when the laser dislocation distance and translational distance are less than 1 and 16 mm, respectively, the flange height error does not exceed 0.06 mm. Subsequently, static experiments and dynamic field tests are conducted to verify the effectiveness of the system. The results show that the system has high accuracy and can achieve real-time measurement of wheelset geometric parameters. The maximum errors (MEs) of the flange height and flange width are less than 0.4 mm. The wheel diameter error and wheelset back-back distance (WBBD) error do not exceed 0.8 and 0.5 mm, respectively. The measurement results can satisfy the requirements of engineering application and maintenance operations.