Using geo-mechanical model test the stresses and stability during excavation and construction of the underground cavities of Jingping Hydro-power Station ClassⅠ were studied by simulating geo-structure, physical and mechanical features of rock, earth stress, process of excavating cavities and bolt-jetting su pport. The effects among three different kind of excavating orders and with and without support schemes are compared. It can be assured that all schemes are tec hnically feasible for adopting whichever excavating schemes. Comparatively, second scheme is better than first or third one. The effect of support measures is o bvious and they can assure cavities stability and safety.