A track irregularity detection system is designed for the current irregularity of the track. The traditional inertial navigation system is directly mounted on the chassis on the carrier, and is a single inertial navigation system. The vibration signal transmission is not direct, and the collected data is not comprehensive. This topic carries out the fixed installation of the dual inertial navigation system through the dedicated inertial navigation platform on both sides of the rail inspection vehicle, and the signal acquisition is more direct and comprehensive. Through the internal navigation calculation, the quaternion method is used to update the attitude matrix in real time. The dual inertial navigation system can realize the real-time acquisition of the X, Y and Z axis three-axis data of the left and right rails, and fitting and integrating the collected data to obtain the relevant irregularity information of the track. And the axle angle encoder with the shaft angle encoder can realize the synchronous acquisition of data, the sampling time and the real-time output of the sampling mileage. The rationality of the design was verified by systematic dynamic testing and artificial static testing. The vertical and horizontal irregularities of the left and right rails are (-0.66mm, 0.52mm) and (-0.43mm, 0.56mm), and the lateral irregularities of the left and right rails are (-0.51mm, 0.64mm) and (-0.42mm, respectively. Between 0.43 mm), the gauge deviation is between (-0.55 mm, 0.83 mm).