The invention relates to a siphoning device. The siphoning device comprises a siphon, a buffering ball (5) and an air exhaust pipe (6), wherein the siphon is composed of a water inlet pipeline (1), a water venting pipeline (2) and an air exhaust branch pipe (3); the water inlet pipeline (1) is communicated with the water venting pipeline (2), and the air exhaust branch pipe (3) is connected with one side of the water venting pipeline (2); the air exhaust branch pipe (3) is connected with one end of the buffering ball (5), and the other end of the buffering ball (5) is communicated with the air exhaust pipe (6); a switching device (7) is arranged on the water venting pipeline (2); in the whole siphoning device, a water venting port of the water venting pipeline (2) is the lowest, and a connection point of the water venting pipeline (2) and the air exhaust branch pipe (3) is lower than the lowest point of the water inlet pipeline (1); a water inlet port of the water inlet pipeline (1) is higher than the lowest point of the water inlet pipeline (1); and an upper end opening on the surface of the buffering ball (5) is not higher than an initial height of a liquid surface to be siphoned. According to the siphoning device, backflow generated during siphoning is avoided, siphoning can be uninterruptedly performed, and the accuracy of extraction results is higher.