The invention discloses an urban storm sewage pipe network deep water quality sampling device with an automatic up-down function. The device comprises a buoyancy tank, a sampling tank, a sample storage mechanism, a negative pressure generation mechanism and a controller, wherein the sampling tank is fixedly connected with the bottom of the buoyancy tank; the sample storage mechanism is arranged inthe sample tank; the sample storage mechanism is provided with a water inlet and a gas outlet; the water inlet of the sample storage mechanism is provided with a first valve; the gas outlet of the sample storage mechanism is provided with a second valve; the gas outlet of the sample storage mechanism is communicated with a gas inlet of the negative pressure generation mechanism; a water inlet hole is formed in the bottom or the side wall of the sampling box; the water inlet hole of the sampling box is communicated with the water inlet of the sample storage mechanism; a third valve is arrangedat the end, far away from a storage tank, of a water sampling pipe; and the controller is in control connection with each of the buoyancy tank, the first valve, the second valve, the third valve andthe negative pressure generation mechanism. The urban storm sewage pipe network deep water quality sampling device with the automatic up-down function is capable of adjusting the sampling depth and sampling amount according to different sampling requirements, so that the sampling accuracy is improved.