Based on the jacking force theory used in circular pipes, the development law and influencing factors of thrust force of rectangular pipe jacking tunnel group are analyzed through 7 working conditions in actual experimental engineering. The uniformity of the monitored pipe jacking force and theoretical values is verified by comparison between theoretical estimation and monitored data, and it is concluded that the theoretical values are smaller than monitored data. And then the problems of friction reduction, the phenomenon of pipe carrying soil, and attitude deviation are studied. Finally, by comparatively analyzing the development law of thrust force in different working conditions, it is concluded that: (1) The friction reduction effect of lubricating mud is obvious, i.e. the thrust force is reduced by about 38.2%. (2) The phenomenon of pipe carrying soil and attitude deviation greatly affect the thrust force, wherein the thrust force of each segment induced by the phenomenon of pipe carrying soil is increased by about 16.7%, and that induced by attitude deviation is increased by 17.8 of pipe force. 