Abstract: Triton X-114, an non-ionic surfactant, was modified with the affinity ligand of trypsin,p-aminobenzamidine (PAB) and the affinity surfactant (PAB-TX) was synthesized.Then, the affinity surfactant was used to prepare affinity-based colloidal gas aphrons (CGA).The stability of the affinity CGA was investigated at different temperatures and compared with that of the CGA prepared from Triton X-114.Compared with the CGA from Triton X-114, the affinity CGA showed high selective adsorption property for trypsin.In the separation of a protein mixture,recovery yield higher than 74% were achieved for trypsin and the separation factor reached over 1.5.The results showed that the affinity CGA possessed promising selectivity for separating trypsin from a protein mixture.