Protection method for ambient environment in processes of excavation and precipitation of foundation pit

The invention discloses a protection method for an ambient environment in the processes of excavation and precipitation of a foundation pit at a collapsible loess region, which concretely comprises the following steps that: a hanging type waterproof curtain (6) is constructed at a water-containing soil layer (3) after the construction of an enclosure structure (8) of a foundation pit (9) is finished, and the top end of the hanging type waterproof curtain (6) is higher than the underground water level but does not penetrate through the water-containing layer (3); afterwards, a precipitation well (10) is constructed; and meanwhile, a recharge well (6) is arranged between the foundation pit (9) and a peripheral building (5), the recharge well (6) penetrates through a collapsible loess layer (2) but does not penetrate through the water-containing layer (3), and a water filtering hole below a soil layer (2) is arranged at the recharge well (6). In the process of excavation of the foundation pit, the water level is lowered to a designed elevation by using the precipitation well (10). Meanwhile, the condition that the water level of the recharge well (6) is lower than the soil layer (2) is kept by utilizing the recharge of the recharge well (6). The technical scheme provided by the invention not only can meet the requirement of precipitation in the excavation of a foundation pit at a collapsible loess region but also can be used for protecting the safety of a building at the periphery of the foundation pit, saving water resources and lowering the cost.