The track geometry state measuring instrument using GNSS positioning cannot work in GNSS rejection environment such as tunnel and underground.Since the railroad track is still close to the design alignment even if it is deformed,the difference between actual track position and its design value always remains within a certain range.Herein,a track irregularity detection approach considering design attitude assisted IMU／ODO (Inertial Measurement Unit／Odometer) is proposed,which combines design attitude with inertial guidance solved attitude for Kalman filtering and uses odometer velocity for dead reckoning.Computational experiment results show that the railroad design attitude information can significantly improve the track irregularity detection accuracy,and the proposed approach is comparable to the total station assisted dynamic detection method according to the 30 m chord track irregularity detection results.The overall detection efficiency is high enough to meet the needs of daily track detection.