The utility model discloses an adjustable front balance weight mechanism. The balance weight device comprises a balance weight frame fixedly arranged on a tractor rack, a balance weight block assemblyis installed on the balance weight frame in the front-back direction in a sliding mode, a sliding connection device and a sliding drive device are arranged between the balance weight block assembly and the balance weight frame, and the sliding drive device is connected with a drive control device. According to the utility model, the balancing weight assembly can be adjusted in a sliding manner; the whole gravity center of the tractor body can be adjusted front and back, so that when the tractor body is subjected to acting force of different machines and tools, the position of the whole gravity center of the tractor can be kept stable through adjustment of the balancing weight assembly, distribution of loads of the front shaft and the rear shaft can be in a reasonable state, and effectivetraction of the tractor is guaranteed.