With the aid of CJENC system，we explore the dynamic calculation mathematical models and algorithms of the navigable waters，by which，we can calculate and update the navigable water scope and its dynamic centerline according to the user’s specific demand on the water depth and combining with the real-time or predictive water levels，so as to assist the ship’s pilotsto to confirm the navigable waters and select reasonable routes.The key points of the study are the selections of appropriate dynamic interpolation algorithm of depth data，TIN model generation algorithm，depth contour tracking algorithm，depth contour smoothing algorithm，etc.With the secondary development functions and various spatial analysis tools of ArcGIS，we finally implement the dynamic calculation toolset of navigable waters in CJENC.