With the development of opening up to the world, the scale of medium sized cities are be- coming larger. The trip distance becomes longer accordingly. As the result, the trip modes have been changing. This paper analyzed the developing trend of pubic transport in medium sized cities on the basis of resident trip characteristics and the problems of present pubic transport network. The idea of optimization of network was put forward, which could serve as useful references for success- ful transfer of transport struction in medium sized cities.