Abstract: With the necessary carbon source for cell culture， glucose and citric acid and the nitrogen source- L-glutamic acid as the small molecul models，and a series of poly(ethylene-glycol)s (PEG) of different molecular weights as the large molecule models，the permeability of chitosan/alginate microcapsules was studied and the influence of preparation conditions on microcapsules permeability was investigated. Experimental results showed that glucose，L-glutamic acid，citric acid could diffuse through the membrane into the microcapsules，the molecular mass cut-off (MMCO) of microcapsules prepared from 20 mg/mL sodium alginate and 2 mg/mL chitosan of molecular weight 50 000 was approximately 1500，and the peameability of chitosan/alginate microcapsules increased with the decrease of the concentration of chitosan solution and chitosan molecular weight，and the increase of microcapsule diameter.