The development of graphene-based room-temperature NO2 sensors with high sensitivity remains a challenge. Herein, a wet-chemical etching strategy is investigated to introduce oxygen vacancies onto SnO2-RGO using ethanolamine (EA) as etching agent, thereby improving the NO2 response of room-temperature NO2 sensors. The oxygen vacancies-rich SnO2-RGO (EA-SnO2-RGO) is simply prepared by stirring SnO2-RGO in EA solution at room temperature, which not only decreases the size of SnO2 particles in EA-SnO2-RGO, but also introduces additional oxygen vacancies onto SnO2 particles surface. Notably, EA-SnO2-RGO sensor presents a high response value of 5.8 (1 ppm NO2) at room temperature, that is 2.1-fold larger than the response value for SnO2-RGO. Simultaneously, EA-SnO2-RGO sensor also demonstrated short response time (95 s) and good selectivity, indicating huge potential applications for room-temperature NO2 detection. This study provides new strategy to fabricate high-performance gas sensors operated at room-temperature.