Abstract: With a condensation reaction of heterogeneous long chain alkyl fatty acid and dimethyl propylene amide, the heterogeneous long chain alkyl tertiary amine intermediate was obtained, which made an oxidizing reaction with oxidant, and then a kind of heterogeneous long chain alkyl amphoteric foaming agent was synthesized. The optimum conditions for the synthesis of the foaming agent are as follows: the condensation reaction temperature is 150 ℃, the molar ratio of reactants is 1: 1.04, the reaction time is 8 h; the oxidation reaction temperature is 85 ℃, and the molar ratio of reactants is 1: 1.2. The viscosity of foaming agent solution reduced to 26.7 mPa·s, surface tension was only 28.3 mN/m. Indoor evaluation was conducted under the condition of 20 vol% condensate oil: foaming height was 167 mm, liquid rate reached 65%; foaming agent resistance temperature was 90 ℃, salinity resistance was up to 200 g/L. The field application was carried out in 5 wells in Sulige gas field (condensate oil content is less than 20%). The gas production increased 30% after filling the foaming agent into gas wells.