Abstract: Bovine serum albumin (BSA) -locust bean gum-chitosan sustained-release microspheres were prepared by cross-linking method using locust bean gum and chitosan as carrier, glutaraldehyde cross-linking agent and BSA model drug. The effects of different glutaraldehyde concentration, the ratio of carrier to BSA and water to oil phase, and cross-linking time on microspheres preparation were investigated by single factor experiments.The resulting microspheres were characterized by infrared spectrum, thermogravimetric analysis, element analysis, dynamic light scattering and morphology analysis. At the same time, its releasing property was also determined. The results showed that the optimal preparation technology for microspheres were glutaraldehyde concentration 1.25%, the ratio of carrier to BSA and water to oil phase 20∶1 and 6∶1, respectively and crosslinking time 60 min. Under these conditions, encapsulation efficiency and drug loading for microspheres were62.32%±0.39% and 3.45%±1.43%, respectively. The morphology of microspheres was in uniform size with the average diameter of 80 nm. The microspheres had certain sustained-release capability, and their releasing rate was as follows:small intestine>stomach>large intestine.