Abstract: Evaluation of the public transport network is a precondition and the fundamental work for improving and optimizing the transportation system of a city. 6 key indices were put under careful examination and by adopting the GIS technology an evaluation was made of the status quo of the public transport network in the city of Nanchong. The following problems are found: the traffic lines being too redundant; too great a non-linear coefficient of traffic lines; too low a network coverage for the public traffic lines; the repetition rate of the lines in the inner city being too low; too many overlapping lines in some local areas; and too sharp a decrease in line density from the inner city to the urban fringe. At last, some pertinent suggestions were given for improving the bus line network structure