Owing to complaxity of geological conditions and limitation of explorating work before construction, revision and alteration of the design of construction details are normal things in construction stage. Alterable Geo-design includes the following ways. First, design before construction is prepared to fully alter. Then, new geological, deformation and failure informations and their engineering significance are fed back immediately. Last, according to these, the design is altered and revised with the assistance of CAD and returns to construction repidly. The authors take some real engineering examples to illustrate that feeding back and analysing these informations and ensuring normal flow of them are the key for optimum design. It is necessary to bring the design into design norm formally.