The scale of the Three Gorges Project's(TGP's) safety monitoring system is enormous and its tech nology complex.On the basis of primary design,it is necessary to develop optimum research for this system.Based on the general principle of monitoring arrangement of "laying emphasis on key points,considering overall situation,uniting planning and implementing plan by stages",aiming at the features of the different structures and their foundations,taking the deformation monitoring,seepage monitoring,stress monitoring and temperature monitoring as key points,the optimum objectives were determined,researched and good results obtained.Among them,the number of instruments used for deformation monitoring and seepage monitoring,as well as those used for hydraulics monitoring and dynamic monitoring,may be reduccd by about 1/2,and those used for stress monitoring and temperature monitoring,by about 2/3.Most of the study results were adopted in the tender design and construction detail drawing.