The invention discloses an auxiliary foaming agent and a preparation method thereof. The auxiliary foaming agent is prepared by uniformly stirring attapulgite, zeolite and calcite, soaking the mixture in diluted hydrochloric acid of which the concentration is 0.5 to 6 weight percent, drying the mixture, crushing the dried mixture into powder, blending the powder and powdery white carbon black anduniformly stirring the mixture, wherein the weight ratio of the attapulgite to the zeolite to the calcite to the white carbon black is (0.3-0.8):(0.02-0.6):(0.1-0.8):(0.01-0.8). The auxiliary foamingagent disclosed by the invention has high liquidity and dispersibility, makes a foaming agent move to the direction with little ammonia gas to the greatest extent and can absorb and react the generated ammonia gas at the same time.