Abstract: A gas purifying device for energy saving and preventing spraying waste water indiscriminately includes: a container (103) containing a proper quantity of purifying liquid; a waste gas incoming pipe (101) having a channel mouth (102) for introducing waste gas, wherein the channel mouth (102) is contacted with and provided in the purifying liquid in the container (103) and is submerged by the purifying liquid; and safe gas discharge channels (107, 109) for purified gas. A cross-sectional area of a narrowest part of the safe gas discharge channel (107, 109) is greater than a smallest part of the waste gas incoming pipe (101), so as to ensure a smooth operation of the gas discharge channel. The gas purifying device solves problems of regular engine flameout due to the non-smooth gas discharge of a purifier and environmental pollution caused by spraying waste water indiscriminately in the purifier working process.