In order to further reduce the cost and to improve the imaging speed and accuracy, a full field time-domain optical coherence tomography (OCT) system based on light-emitting diode (LED) illumination was proposed. The LED was used as the light source and the closed-loop four-step phase-shifting method with feedback was used to collect signals. Its imaging principle was described, and the system structure was studied, theoretical analysis and experimental verification were carried out. The results show that the coherence length of the system is 23 μm, the axial resolution is 11.8 μm, the lateral resolution is 19.8 μm, and the acquisition time of single image is 2.15 ms, respectively. Compared with the previous OCT scanning methods, the implementation cost is reduced by this method, and the scanning rate and accuracy is respectively faster and higher, which meaning great application value. This research provides a reference for the development of ultra-high speed, high precision and low-cost OCT system.