The chitosan nanosphere is formed by the ion gel and charactered by TEM.The encapsulation efficiency and controlled release of chitosan nanoparticles for BSA are studied.The result suggests that the high encapsulation efficiency and loading of BSA reach 86% and 49%,the BSA encapsulation efficiency and the BSA loading are affected by the initial CS concentration and the initial BSA concentration,the higher the initial CS concentration,the higher the BSA encapsulation efficiency and the BSA loading.However,it shows opposite trend when the initial BSA concentration increase.The BSA loading increase,but the encapsulation efficiency decrease.The TPP concentration has little influence on BSA encapsulation efficiency.The behavior of chitosan nanospheres for BSA in vitro release revealed a controlled and continuous release of the entrapped protein after 12 hours and released 30% of the BSA loading within 3 hours.