To meet some special requirements of 2D displacement measurement in engineering or improve the efficiency of displacement measurement, a simple and compact dual-channel displacement measurement system utilizing laser self-mixing interference is established. Firstly, mathematical equations of the self-mixing interference system are given, which are based on the three-mirror Fabry-Perot cavity model. Then, under the condition of weak feedback, linear current modulation is applied. According to the linear relationship between the frequency of the self-mixing signal and the distance between the external object, when the distance between the two objects and the laser is different, the frequency domain will present two independent spectral peaks, and the phase is solved respectively. Therefore, the self-mixing dual-channel displacement measurement is realized. Then, the dual-channel self-mixing signal is generated by numerical simulation. The phase of two spectral peaks of the self-mixing signal is extracted according to the all-phase spectrum analysis technique, and the displacement curves of the two objects are reconstructed accordingly. Finally, an experiment system is established, the dual-channel displacement measurement experiments are carried out, and the measurement results are exhibited subsequently. The experimental results show that the system can completely distinguish two moving objects, and the relative error of displacement measurement is better than 8. 42% . The linear frequency modulated laser self-mixing interferometry can realize the dual-channel displacement measurement of arbitrary motion, and the number of measuring channels can be further increased by more beam splitting.