The invention discloses an amphibious robot capable of moving on flat ground with wheels and surmounting obstacles with legs and a working method of the amphibious robot. The amphibious robot comprises a chassis, wherein at least two groups of wheels are symmetrically arranged on two sides of the chassis, and all the wheels are driven by corresponding wheel driving motors; at least two groups of obstacle surmounting feet are symmetrically arranged on the two sides of the chassis, all the obstacle surmounting feet are driven by corresponding module motors, and the obstacle surmounting feet adopt an arc-shaped structure; a distance sensor is arranged on the edge in the advancement direction of the chassis, and the distance sensor, all the wheel driving motors and the module motors are all fixed on the front surface of the chassis. According to the amphibious robot disclosed by the invention, the amphibious robot moves through the wheels on the flat ground; when encountering obstacles, the amphibious robot can surmount the obstacles through the obstacle surmounting feet; when entering water, the amphibious robot can float through the chassis and can paddle in water to advance through the obstacle surmounting feet. The amphibious robot disclosed by the invention selects different motion modes according to different environment, and the environment adaptability and the working efficiency of the amphibious robot are improved.