Starting from the fact of contemporary urban problemsexsiting universally,this paper traces back and analyses the theoreticalpoints of green city and its widespread and profound influence.Thispaper also expounds its benefit and enlightenment to us.To relax thesevere urban ecological and environmental problems,the author,consci-entiously drawing some modern urban planning thoughts such as gardencity,organic dispersion and systematical coordination and based on thepractice in the over all planning of Leshan city,presents a new conceptof green core city aiming to combine overall city planning with ecologyplanning and layout structure with improving urban living quality bylaying the city in several natural ecological circles.It will creat a higher urban living environmental quality.To satisfy demand of contemporarycities on a higher stage of development for environmental quality,it isnecessary to achieve the developmental goal of ecological city.This paperstates this point of veiws on the meaning and basic requirements for anecological city and stresses that it is important to raise the view ofunifying economical and social benefits with ecology and environment inurban planning and construction.