A novel mesoporous TiO2@g-C3N4 hollow core@shell heterojunction photocatalyst was engineered for the first time by in situ calcining and growing of cyanamide (CY) on the surface of TiO2. The HTCN-1 possesses good structure and performance when the addition amount of CY is 1 mL. HTCN-1 shows high photocatalytic activity toward congo red (CR), rhodamine B (RhB), phenol and ciprofloxacin (CIP) with degradation efficiencies of 97%, 100%, 73%, and 74%, respectively. HTCN-1 also displays high photocatalytic activity for H-2 generation at rate of 7.9 mu mol h(-1). A possible charger transfer mechanism and photocatalytic degradation mechanism of HTCN-1 are proposed basing on the experiment results. The enhanced photocatalytic activity may be attributed to the higher charge transfer efficiency of photogenerated electron-hole (e(-)-h(+)) pairs caused by close contacts, a larger interfacial area, and the higher barrier for conduction bending. What's more, HTCN-1 possesses relatively high stability during the entire photoreaction process. Given the unique spatial structure and superior photocatalytic characteristics of the HTCN-1, there is great potential for applications in water treatment and H-2 generation.