This paper presents the items of great importance such as the selection of coordinates, grid interval, in addition to the treatment techniques of line-boundaries like breakwaters, the mouth of breakwaters, permeable marine strutures, and flow-controlling at open boundaries on tidal simulation.
　The area concerned, the direction of coordinates, and grid interval have a great influence on the results and cpu (central-processing-unit) time, it is, therefore, necessary to take care of their determinations. The jigzag flow generated in the process of small mesh simulation can be removed by lateral-mixing terms of momentum equations. The reproducibility of flow field can improve by flowcontrolling or flow-and-elevation-controlling, in case of the area of prominent permanent current, or of the area too narrow to estimate the geographical permanent current at open boundaries.