Hydrogen peroxide (H2O2) is an important messenger molecule in vivo. The next generation sensor demands for intelligence and integration. Three-dimensional nanosheet structure is of considerable interest for the development of highly stable and sensitive sensor. This paper describes the synthesis of self-assembly vertically cross-linked 3D Bi3Ti2O8F nanosheets/Au (3D-BTOF Ns/Au) electrode. And its application as a high effective H2O2 sensor was explored. The combination of colorimetric and electrochemical sensing, plays a synergistic role in the qualitative and quantitative detection of H2O2. Colorimetric sensing was applied to identify the existence or not of H2O2. Amperometric measurements were further performed to quantitatively detect H2O2. The 3D-BTOF Ns/Au sensor showed an outstanding sensitivity of 1764 mu A mM(-1) cm(-2), response time of 2 s and low detecting limit of 1.43 mu M. The unique vertically cross-linked structure provides abundant electroactive sites for adherence of H2O2. Particularly, the layered intergrowth structure of [F-Bi-O-Bi-F] sheets can induce an internal electric field (IEF), which greatly benefits to the separation of electron-hole pairs. Appling the traditional Ti/Bi-based materials into the emerging sensing field is a successful attempt. The constructed 3D-BTOF Ns/Au electrode holds promise as "a health guardian" for a real-time sensor to detect H2O2.