The invention provides a light and simple harvesting machine which comprises a crop pulling wheel, an inclined conveyor, a threshing cylinder, a screening and conveying auger, a grain tank, a grain conveying auger, a drum sieve, a control console and a header. The crop pullling wheel is arranged on the header and used for pulling up crops to be cut by cutting knives in the header. One end of the inclined conveyor is connected with a discharging opening of the header, and the other end of the inclined conveyor is connected with a feeding opening of the threshing cylinder. A discharging opening of the threshing cylinder is connected with one end of the screening and conveying auger, and the other end of the screening and conveying auger is connected with a feeding opening of the drum sieve. The grain conveying auger is located on the lower inclined portion of the drum sieve. The grain conveying auger is in an L shape, and the output end of the grain conveying auger is connected to the grain tank used for storing crops. According to the harvesting machine, screening is conducted through the drum sieve which is rotating movement equipment without a center axis, the mass of the whole machine is lowered, rotating is steady, noise is less, impact is less, and the service life is longer.