Constructing highly efficient and stable catalysts for tetracycline degradation is very important in avoiding harm to human and ecosystem health. Herein, we doped Co-MOF into carbon nitride (CN) and synthesized successfully a copolymer Co-CN with heterojunctions structure simple intramolecular doping. Various characterization results demonstrate that Co2+ cations are highly dispersed on the CN support. The Co-CN catalyst exhibited outstanding degradation efficiency and recycle stability for tetracycline (TC) degradation, demonstrates a degradation efficiency of 85.2% under benign conditions. Various characterization results revealed the pathway and mechanism of TC degradation. An intramolecular heterojunction structures in Co-CN copolymers promote charge separation and transport efficiency, which make a variety of active species to be generated in the reaction system. Free radical trapping experiment results show that four active species including h+, 1O2, •O2− and •OH synergistically catalyze to activate the substrate to achieve degradation of TC molecules.