In the case of a typical circular deep foundation pit with a diameter of 10.0m and a depth of 24.50m in the eastern suburb of Xi’an， in order to solve the difficulties in excavating a pipe jacking well with a small size and a large depth in the loess area collapsible under overburden pressure， including the extremely complex surrounding environment， close proximity of the working well to multi-storey buildings which are extremely sensitive to deformation， no anchor cable construction space， the circular reinforced concrete was used to resist the earth pressure instead of the traditional inner support， which not only eliminated disturbance on the excavation in the narrow space， but also controlled the deformation of the enclosure structure and protected the safety of the surrounding environment. Several engineering practices show that in a circular deep foundation pit with a diameter of less than 12m and a depth of no more than 25m， the designed system has low cost， small deformation with the enclosure structure， safe and reliable surrounding environment， no anchor rod （cable） remaining in the soil， and no impact on the later development and utilization of the adjacent underground space， which provides reference for excavating similar deep foundation pits in the loess area collapsible under overburden pressure.