Traffic volume forecast of urban river-crossing channel is the basis and premise of construction of urban river-crossing channel. By analyzing characteristics of traffic volume of urban river-crossing, a method of traffic volume forecast of urban river-crossing channel was put forward. Firstly, components of traffic volume of urban river-crossing channel were analyzed. Secondly, the OD matrix was divided into urban internal transportation and interurban transportation. Two different forecast methods were adopted, and results of the two parts calculated by different methods were added to work out the total traffic volume of urban river-crossing channel. Thirdly, the total traffic volume was allocated to several river-crossing channels by calculation, and the traffic volume of each river-crossing channel was gained. The method proposed in this paper was proved to be effective by the example calculation of river-crossing channel of Fu Ma Yangtze River Bridge in Wan Zhou district of Chong Qing.