Front transmission mechanism of seed-metering device, seeder and seed-metering method

The invention relates to a front transmission mechanism of a seed-metering device, a seeder and a seed-metering method. The front transmission mechanism comprises a driving wheel part and a driven wheel part, the rotating shaft of the driving wheel part is matched with the driving unit in an associated manner, and the rotating shaft of the driven wheel part is matched with the seed sowing device in an associated manner. A section of first tooth surface is formed on the outer peripheral surface of the gear of the driving wheel part; n sections of second tooth surfaces are formed on the outer peripheral surface of the gear of the driven wheel part, a locking arc is formed between every two adjacent sections of second tooth surfaces, and N is a natural number larger than or equal to 3. And after the gear on the driving wheel part is correspondingly matched with the gear on the driven wheel part, the first tooth surface can be sequentially meshed with the second tooth surfaces, and the outer peripheral surface of