The large-scale consumption and discharge of antibiotic tetracycline (TC) urge us to search for a highly efficient and eco-friendly technology to remove it. In this work, face-contact ZnSnO3@g-C3N4 core-shell heterojunction was successfully constructed via one-step calcination route. The experimental data indicate that the photocatalytic TC removal performance of ZnSnO3@g-C3N4 (1:3) reaches 90.8% within 120 min under the same condition compared with bulk g-C3N4 (32% degradation) and ZnSnO3 (9% degradation). The improved photocatalytic activity is ascribed to the formation of core-shell structure between ZnSnO3 and g-C3N4 which not only enlarges visible light response but also effectively separates electron-hole pairs. Meanwhile, this face-contact ZSO-CN photocatalyst displays much more contact interfaces than the point-contact ZSO-CN photocatalyst, and the contact interfaces could play the part of efficient channels for charge transfer. Finally, the photocatalytic reaction mechanism on ZnSnO3@g-C3N4 was also stated at length through active species capture and electron spin resonance (ESR) tests. And the possible intermediates products were discussed through the liquid chromatography-mass spectrometry (LC-MS) analysis.