Combined with water well construction, the application researches on solid-free weak gel drilling fluid and enzyme breaker fluid were carried out. The weak gel drilling fluid has unique rheological characteristics, high yield point-plastic viscosity ratio (YP/PV), high low-shear rate viscosity (LSRV) and strong sand carrying capacity. In addition to cooling drill bit, clearing rock cuttings in bottom of the hole and protecting borehole wall, another advantage of this drilling fluid is solid free, so that it is not easy to clog the formation pores, and it reduces aquifer damagecaused by the solids in drilling fluid. If enzyme gel breaking agent is added to drilling fluid, it helps to clear out the filtrate cake in the well and dredge water channels in the formation and achieve better single-well yield and permeability coefficient, which provides a new method for strengthening aquifer protection in the well construction.