The invention discloses an open pet hair drying device which mainly comprises a U-shaped space and hot-air blowers. The U-shaped space for accommodating a pet comprises two side plates and a bottom plate, the two side plates are symmetrically arranged, concave cambered surfaces are arranged on the inner walls of the side plates and the inner wall of the bottom plate, a plurality of air outlets are uniformly formed in the inner walls of the side plates, hot air can be respectively obliquely upwardly, horizontally and obliquely downwardly blown out of the air outlets, the hot-air blowers which generate the hot air are arranged at joints of the side plates and the bottom plate, filter holes are formed in the bottom plate, water which drops from the body of the pet is collected into a water collecting tank via the filter holes, the water collecting tank is provided with an observation window, the quantity of the water in the water collecting tank can be observed, the water collecting tank can be drawn out to be cleaned when filled with the water, a timer, an air volume regulator and a temperature regulator are arranged on the outer wall of each side plate, and the time, the air speed and the temperature can be controlled in a drying procedure. The open pet hair drying device has the advantages that hair of the pet can be dried in an open manner, a speedy and efficient drying effect can be realized, the pet can be in close contact with an owner and can be freely communicated with the owner in the integral procedure, and accordingly a nervous and fretted mood of the pet due to hair drying can be relieved.