Given the present synthesis method of constructing a dual Z-scheme photocatalytic system, the accurate interface structure design remains a challenge. In this work, 0D/2D/1D AgI/BiOI/C3N5 dual Z-scheme heterojunctions with confined interface structures were fabricated by combining a room-temperature precipitation strategy with an ion-exchange route. Tetracycline hydrochloride (TCH) photodegradation under simulated visible light illumination was conducted to evaluate the photocatalytic activity of the as-prepared dual Z-scheme heterojunctions. Compared with the single component as well as the counterpart single Z-scheme heterojunctions, the constructed dual Z-scheme heterojunctions displayed superior catalytic activity. The apparent kinetic constant of the optimized AgI/BiOI/C3N5 nanocomposite was 410.2, 3.2 and 2.1 times as high as the bare C3N5, BiOI and AgI. The enhanced photocatalytic activity was attributed to the efficient charge separation of dual Z-scheme photocatalytic mechanism supported by systematical characterizations. It is anticipated this work can be a guide for the construction of a dual Z-scheme photocatalytic system.