The invention provides a negative pressure anti-backflow urine bag, comprising a bag body, a drainage tube, a negative pressure unit, and a backflow prevention valve unit. The bag body defines an accommodating space and includes an input port that communicates with the accommodating space. The drainage tube is connected to the input port of the bag body and defines a drainage channel. The negative pressure unit is disposed on the drainage tube and includes a negative pressure ball and a switch defining a filling space. The filling space of the negative pressure ball communicates with the drainage channel of the drainage tube, and the negative pressure ball has a pressure relief joint connecting the drainage channel of the drainage tube and the filling space. The switch is disposed on the negative pressure ball and can close the pressure relief joint. The anti-backflow valve unit is disposed in the drainage channel of the drainage tube and located between the negative pressure unit and the input port of the bag body.本新型提供一種負壓防逆流尿袋，包括一袋本體、一引流管、一負壓單元，及一防逆流瓣膜單元。該袋本體界定出一容置空間，並包括一連通該容置空間的輸入口。該引流管連接於該袋本體的輸入口，並界定出一引流通道。該負壓單元設置於該引流管，並包括一界定出一填充空間的負壓球及一開關。該負壓球的填充空間連通該引流管的引流通道，且該負壓球具有一連通該引流管之引流通道與該填充空間的洩壓接頭。該開關設置於該負壓球上，並能封閉該洩壓接頭。該防逆流瓣膜單元設置在該引流管之引流通道內，並位於該負壓單元與該袋本體之輸入口間。
