A method of preparing methoxypoly (ethylene glycol)-poly-DL-lactide (PELA) microcapsule containing bovine hemoglobin(BHb) by using W/O/W double emulsion-solvent diffusion process for use as artificial red cells was developed. The results suggested that preparation conditions such as solidification method, stirring rate, type of organic solvent had significant influence on the encapsulation efficiency and the activity of bovine hemoglobin. When ethyl acetate was used as the organic solvent and double emulsion-solvent diffusion process was used, there was no significant influence on the activity of hemoglobin if stirring rate was lower than 9000 r/min. High stirring rate, 12,000 r/min, decreased the P(50) and Hill coefficient of the hemoglobin encapsulated. Increasing the volume of solidification solution had an effect of improving the activity of hemoglobin to carry oxygen.