The utility model discloses a delayed visbreaking device which belongs to the field of petroleum refining processing technologies. The device comprises a first reaction tower and a second reaction tower, wherein the lower end of the first reaction tower is connected with a heating furnace, the upper end of the first reaction tower is connected with a fractionation tower, the lower end of the second reaction tower is connected with the heating furnace through a first pipeline, the upper end of the second reaction tower is connected with the fractionation tower, a first valve is arranged between the first reaction tower and the heating furnace, a second valve is arranged between the first reaction tower and the fractionation tower, a third valve is arranged on the first pipeline, a fourth valve is arranged between the second reaction tower and the fractionation tower, the upper end of the first reaction tower is connected with the lower end of the second reaction tower through a second pipeline, a fifth valve is arranged at the upper end of the second pipeline, and a sixth valve is arranged at the lower end of the second pipeline. In the delayed visbreaking device, the one-section up-flow type reaction tower is changed to be the two-section up-flow type reaction tower, thereby improving the operation effect of the reaction tower, being flexible to operate and realizing the purpose of clearing inside the towers respectively without the shutdown of the device.