Abstract: In this paper, orthogonal test was used to optimize the preparation conditions and technique of mitoxantrone ethylcellulose microspheres (DHAQ-EC-MS) for liver embolization. The dynamic osmosis method was used to study the drug release characteristics of DHAQ-EC-MS. DHAQ-EC-MS suspension for clinical liver artery embolization was prepared. The result showed that the DHAQ EC MS is regular in its morphology with a mean diameter of 110.24±38.19 μm. The drug loading was 12.5% and embedding ratio was 55.6%. The release characteristics was in accord with single exponential model. The drug release equation is lg(Y_∞-Y)=-0.116t-1.198×10^-3 (γ=0.9992, t₅₀=2.6 h). The DHAQ EC MS was shown to be physically and chemically stable and its suspension is suitable for clinical use. Experiments in dogs indicate that drug concentration of DHAQ-EC-MS in hepatic vein blood was higher than DHAQ solution, and the MRT_0～72 was 2.45 times higher than DHAQ solution.