Abstract: The software~development method that combined a BFBdeveloping mode and a building block structure was proposed for fastdeveloping the hydraulics solver, a kind of hydraulics CAI software. Theadvantages of this kind of developing method are that we can make full useof the existing codes, extend the software conveniently, and easilycooperate with others. The software is User-friendly and meets the needs inhydraulics teaching.