Two-dimensional (2D) metal oxides semiconductor is considered as an important candidate material in the field of gas sensing. Here, fabrication of 2D ultra-thin mesoporous WO3nanosheets (WO3NS) was demonstrated by hydrothermal method and morphology-inheritance route. The thickness and specific surface area of the as-prepared 2D WO3NS were 5 nm and 57 m2/g, respectively. It was found that 2D ultrathin mesoporous WO3NS exhibited outstanding enhanced sensing properties for ppb-level C2H6S3detection, which could be ascribed to ultrathin structure and edge effect of mesoporous structure. The response of sensors based on 2D ultrathin WO3NS towards 5 ppb was 1.6, which is very helpful for the identification of biomarkers. In addition, the 2D ultrathin WO3NS show rapid response, and high selectivity to ppb-level C2H6S3.