According to the theory of ndustrial location,This paper researches the prinicple of dividing grades of city's commercial centre, and divides the city's commercial centre into four grades,Thery are city centre,district centre,residential quarter centre and.small reteil network,it also researches the function model of commercial centre and the" features of W.Christaller's location distribution.The writer has researched deeply the forming causes conelitions and development activity of commercial centre in Lanzhou,and according to the principle of traffic style of central place theory,he analyses the presental gradation structure of commercial centre in Lanzhou and drawed a picture of location pattern net of commercial centre. The result indicated, the distribution of commercial centre is basically in comformity with the principles of triangle settlement market frame of sexangle and step gradation structure,This paper proposes a concept of location Advantage Acgree of city's commercial centres and defines it as the quantitative description, which shows the advantage degree of that the commercial centre engages in business activity;It may be divided Location Advantage Degree into two concepts of basic location advantage degree and realistic location advantage degree and establised two mathmatic models for calculating them.By means of the observed and measured data,the writer pursues specific computation and analysis. The result indicated that among the presental four city commercial centres, zhangye street centre has advantage, the second is West-railway-station centre and the advantage of panxuan street centre and xign central stveet are Worse. Then he made a corresponding analysis to their development potentiality.Finally,the writer symthesizes above mentioned qualitative and quantitative result and gived some suggestions of disposing rationally the commercial centres and of improvung city's commerce in Lanzhou.