The invention discloses a transmission mechanism on a maize harvester. A power output shaft on the right side of a left ear picking box is connected with a power input shaft of a middle ear picking box through a coupling, a power output shaft on the right side of the middle ear picking box is connected with a power input shaft of a right ear picking box through a coupling, a left power input wheel is arranged on the left side of the left ear picking box, a right power output wheel is arranged on the right side of the right ear picking box, an over-bridge driving shaft with power originated from a diesel engine is rotatably connected to a frame, an ear picking wheel fixedly connected to the over-bridge driving shaft is connected with the left power input wheel on the left side of the left ear picking box through a transmission belt, the right power output wheel on the right side of the right ear picking box is connected with an auger wheel fixedly connected to an auger, and a transmission wheel fixedly connected to a grain seedling pulling transmission shaft is connected with a grain seedling pulling wheel fixedly connected to the auger through a transmission belt; a transmission shaft of a shredding device is connected with a shredding wheel fixedly connected at the left end of the over-bridge driving shaft through a transmission belt, and a delivery driving shaft is connected with a delivery wheel fixedly connected at the right end of the over-bridge driving shaft through a transmission belt.