The invention relates to the application for separating gas from three-phase fluid of gas, liquid and solid, aiming at the request of recycling the gas among the mixed phase of gas, liquid and solid with high efficiency and low cost, the invention provides variable treatment solution being applied for separating gas from three-phase fluid of gas, liquid and solid, the treatment solution can be water solution, oil, oil solution, oil in water emulsion or water in oil emulsion, after three phases of gas, liquid and solid passing through the treatment solution, gas can escape from the solution, while the liquid and solid can be kept in the solution and mixed solution can be obtained. With the application provided by the invention, the gas in the three phases of gas, liquid and solid can be effectively recycling so as to solve the problem that in present petroleum project construction such as the gas drilling the discharge and burning of great amount of impurity gas caused environmental pollution and the waste of gas resources, moreover, the application of the invention has the advantages of fast separating speed, high purity of gas, low rate of loss, simple treating process, low cost, high gas treating efficiency and the gas after being treated being able to be reused.