Abstract: In order to promote the breeding of maize varieties with multi-resistance and high combining ability in the middle and early maturing region of Heilongjiang Province, this paper mainly introduces the material source, breeding process, characteristics, application and breeding experience of Hexi 640.Maize hybrid Heyu 25 was bred by cross combination of Hexi 640 and Hexi 628.Heyu 25 had been popularized and applied in a large area in Heilongjiang Province, with a cumulative promotion area of more than 1 million ha.It had the characteristics of early maturity, disease resistance and high yield.It is suitable for planting in the third accumulated temperature zone of Heilongjiang Province.It has remarkable social and economic benefits and has a wide application prospect.