The invention discloses a quasi-rectangular shield friction inducing regent diffusion test system. The system comprises a soil box which is a box body used for containing test soil; a simulation shield assembly comprising a simulation shield plate and a hydraulic jack, wherein the simulation shield plate is inserted into the bottom part of the soil box from the side surface of the soil box, the simulation shield plate is close to a base plate of the soil box, injection holes are formed in the upper surface of the simulation shield plate, and the hydraulic jack is used for driving the simulation shield plate to move along the direction of the base plate; a soil pressing simulation assembly arranged on the top part of the soil box and used for applying a vertical pressure to the test soil in the soil box; and a friction inducing regent injection assembly connected with the injection holes of the simulation shield plate and used for injecting a friction inducing regent to the upper part of the simulation shield plate through the injection holes. According to the invention, the relative movement generated between a shield and surrounding rock in a quasi-rectangular shield advancing process in the practical engineering can be simulated in a relatively real manner.