Graphitic carbon nitride (g-C 3 N 4 )-based materials are considered promising catalysts for organic waste photodegradation due to their excellent photocatalytic activity and stability. Herein, a ternary thin layer system based on g-C 3 N 4 was prepared by hexagonal boron nitride (h-BN) deposition followed by liquid phase ultrasonic stripping and Ag deposition (marked as Ag-BCN), which increased the specific surface area of g-C 3 N 4 , expanded the corresponding range of the visible-near-infrared spectrum of g-C 3 N 4 and promoted the photo-generated electron–hole pair separation in g-C 3 N 4 to improve the photocatalytic efficiency of pure g-C 3 N 4 . The results showed that after deposition of h-BN and Ag into bulk g-C 3 N 4 and liquid phase ultrasonic stripping, the efficiency of photocatalytic degradation of tannic acid (TA) was enhanced. The efficiency of photocatalytic degradation of TA by Ag-BCN-2 was 84.3% at 90 min, which was 1.6 times the efficiency of bulk g-C 3 N 4 .