Taking the phase I Shipu navigational channel project in Ningbo-Zhoushan port for example,we analyze the unfavorable factors for channel designing under complicated geologic conditions.Furthermore,a series of main scale parameters of channel designing,such as depth,width and turning radius,are calculated based on the formulas given by the specification in operation referring to the Guide for Design of Approach Channels (PIANC).The recommended results are proved by ship maneuvering simulator experiment.The conclusions may serve as reference for the channel engineering design.