A method to prepare gelatin microspheres by heat cross-linking was established.The influence of emulsification conditions on the average size and swelling capacity of prepared gelatin microspheres was fully studied.The optimal emulsification conditions are as follows: the concentration of gelatin solution is 20%;the ratio of water to oil is 1∶5;the emulsification temperature is 50 ℃;the emulsification duration is 30 minutes;the refrigeration duration is 90 minutes;and the refrigeration temperature is 4 ℃.The average size of gelatin microspheres prepared by employing this method is within the range of 50-1 400 μm

and the swelling ratio is within the range of 150%-400%.