Hyaluronan (HA), the consistent glycosaminoglycans in extracellular matrix, is a kind of biomaterials with wonderful biocompatibility. To develop drug release system (DDS) with HA as drug carrier is a new hotspot in the field of pharmaceutics. In this paper, we applied technique of ultrosound and reversed phase (Water/Oil) emulsification to develop dexamethasone (DEX)-HA-STMP cross-linking microspheres (DEX-HA MS) with STMP as cross-linker. DEX-HA MS has a wonderful shape and property of dispersion. There is a negative correlation between diameter of DEX-HA MS and the content of cross-linker, or the content of emulsifier, and a positive correlation between the diameter and CHA . When CHA≤1%,DEX/HA≤1/10 (g/g),there is a positive correlation between the factors mentioned below and drug loading (DL%)/loading efficiency (LE%),the content of STMP, the content of emulsifier,CHA and the content of DEX. DEX-HA-MS can realize function of slow release. In vitro drug release experiment shows that cumulative release (CR%) of DEX-HA MS fits in with pervasion-corrosion equation, and there is a negative correlation between the content of STMP, CHA and CR%, a positive correlation between emulsifier and CR%. When DEX/HA≤1/5 (g/g) there is a negative correlation between the content of DEX and CR%. Hyaluronan (HA), the consistent glycosaminoglycans in extracellular matrix, is a kind of biomaterials with wonderful biocompatibility. To develop drug release system (DDS) with HA as drug carrier is a new hotspot in the field of pharmaceutics. In this paper, we applied technique of ultrosound and reversed phase (Water / Oil) emulsification to develop dexamethasone (DEX) -HA-STMP cross-linking microspheres (DEX-HA MS) with STMP as cross-linker. There is a negative correlation between diameter of DEX-HA MS and the content of cross-linker, or the content of emulsifier, and a positive correlation between the diameter and CHA. When CHA ≦ 1%, DEX / HA ≦ 1 / 10 (g / g), there is a positive correlation between the factors mentioned below and drug loading (DL%) / loading efficiency (LE%), the content of STMP, the content of emulsifier, CHA and the content of DEX. -HA-MS can realize function of slow release. In vitro drug release experiment shows that cumulative release (CR%) of DEX-HA MS fits in with pervasion-corrosion equation, and there is a negative correlation between the content of STMP, CHA and CR%, a positive correlation between emulsifier and CR%. When DEX / HA ≤ 1/5 (g / g) there is a negative correlation between the content of DEX and CR%.