In this study, the microcapsule was prepared by emulsion crosslinking method, using trisodium trimetaphosphate (TSTP) as crosslinking agent. The microcapsule was named OMA-MPs because the mixture of Octenyl succinic starch ester(OSA-starch)，maltodextrin starch and arabic gum were used as raw material. Orthogonal experiment was used in this work to find the relationship between the small diameter of OMA - MPs and preparation factors. The better condition is that the small diameter of OMA-MPs technique was that the stirring rate 400 rpm, the materials concentration 15%, the crosslinking agent concentration 1%, and the volume ratios(w2/w1) 120:100. Due to the processing route without the use of toxic organic solvents, it is expected that these microparticles can be used as delivery vehicles for controlled release of food and drug.