Hollow hydroxyapatite (HAP) microspheres with pores on their surfaces were prepared by in situ conversion reaction of Li-Ca-B glass in phosphate solution. The morphology and phase composition of the microspheres were investigated using SEM, SEM-EDS, XRD and FTIR. The formation and conversion mechanism of the hollow HAP microspheres during the immersion process was studied. The results show that the prepared microspheres possess good hollow structures. The phase of the microspheres is calcium-deficient hydroxyapatite containing B-type CO32-, which is biomimetic. After 600 oC heat treatment, hollow microspheres’ shells are completely composed of calcium-deficient hydroxyapatite containing CO32- and exhibit the necessary mechanical strength. In the phosphate solution, Ca-P-OH hydrate is in-situ formed on the surface of the Li-Ca-B glass and precipitates at the positions occupied by Ca2+ to form microsphere shell, while the pores are formed at the positions occupied by Li+ and B3+. Such structures are good for the preparation of hollow HAP as the carriers of the porous reservoir drug release system