Gust is a common atmospheric condition encountered by wind turbines. Despite the presence of a vast amount of literature on this topic, few of them involve lateral gust influence. Due to this motivation, this paper studies the influence of sinusoidal gusts on a three-bladed VAWT power performance and tries to reveal the flowfield physics of the interaction between the rotor and the gusts. The chimera mesh technique was used to model the real rotation of the rotor and the resolved gust approach (RGA) model in the TAU code developed by the German Aerospace Center (DLR) for the gust simulations. Both the general aerodynamic model and the gust model were validated before the formal calculations. Various influencing factors were considered and their influences on the rotor power performance and flowfield characteristics were analyzed comprehensively. The findings in this study may be helpful for practical applications in wind engineering, such as blade design, atmospheric influence evaluation, field site selection and energy harvest. (C) 2019 Elsevier Ltd. All rights reserved.