Aiming at the special oval scanning structure of airborne dual-frequency LiDAR, the error sources that affect the positioning accuracy of the system are mainly studied, including the eccentric errors caused by the installation of the motor rotor nut and the encoder, the installation error of the scanning mirror and optical adjustment error. The error model of airborne dual-frequency LiDAR is put forward. Based on this model, the effects of various errors on the positioning accuracy of airborne dual-frequency LiDAR are quantitatively analyzed. The results show that these errors will have a great impact on the system′s positioning accuracy and have different effects on the position of each point on the same line. After a variety of errors are coupled, it is difficult to set up the system correction model. Therefore, the introduction of errors should be controlled in the design of the LiDAR structure, device selection, structural processing, system installation and other aspects, and the error should be quantified in the assembly process so as to be corrected easily in the later stage. Attenuating and eliminating these systematic errors has an important impact on the improvement of positioning accuracy of airborne dual-frequency LiDAR systems.