The introduction, utilization and improvement of the maize foreign germplasm are very important taches in maize cross breeding of our country and are also the key to success or failure on our breeding. Our country introduced the maize 78599 hybrid from Pioneer Co. of American, it passed the comparison trial of yield and had the properties of high yield, good quality, disease resistance. Inbred lines “Qi319”, “178”,“Dan599”,“P138”, “Dan598”“K22”etc.all come from 78599 hybrid. They have been more 50 hybrid maize varieties combined with planted for 7.993 million hectares. They were excellent core germplasm resources. In breeding practice, transformed gene was obvious with the effect of improvement between core germplasms.