Disclosed in the present application are a silicon rod grinding machine and a silicon rod grinding method. The silicon rod grinding machine comprises a base, a first silicon rod clamp, a second silicon rod clamp, a rough grinding device and a fine grinding device, wherein the rough grinding device is provided with at least one pair of rough grinding tools which are arranged oppositely; the fine grinding device is provided with at least one pair of fine grinding tools which are arranged oppositely; and the rough grinding device and the fine grinding device are arranged on a position changing mechanism. The first silicon rod clamp, the second silicon rod clamp, the rough grinding device and the fine grinding device are controlled in a coordinated manner, such that the rough grinding device and the fine grinding device in the silicon rod grinding machine are both in a working state at the same time; and the position changing mechanism is controlled to drive the rough grinding device and the fine grinding device to switch positions between a first machining area position and a second machining area position, such that a silicon rod which is clamped by the first silicon rod clamp located in the first machining area position or by the second silicon rod clamp located in the second machining area position can finish the rough grinding operation and fine grinding operation at the corresponding machining area position, thereby improving the silicon rod grinding efficiency and increasing the economic benefits.