Abstract: The shallow-buried rectangular pipe jacking project has gradually increased in recent years. The worldwide researchers have achieved fruitful achievements on thrust, friction and pipe structure. However, there are few researches on the carrying-soil effect of rectangular pipe jacking. So the mechanism of carrying-soil effect is analyzed, and the concept and failure process of the overall-carrying-soil effect are proposed. Four assumptions are proposed to establish the simplified model, and its basic and critical conditions are put forward. Based on the theory of pipe-soil contact, the Coulomb's shear failure strength criterion and the theory of Langham's earth pressure, the prejudgment theory is obtained, which reflects the relationship among overall-carrying-soil effect, jacking length, segment width, pipe soil friction and depth. Then an example is given. The conclusions may provide a theoretical reference for avoiding the overall-carrying-soil effect.