Abstract: OBJECTIVE To prepare aspirin solid dispersion(SD) and capsules, and to improve its dissolution. METHODS Using polyvi-nylpyrrolidone(PVP K 30) as carrier, aspirin SD was prepared by spray-drying method. The dissolution in vitro was determined. X-ray diffractometer and Scanning electron microscope were used to investigate the dispersion status of aspirin in the carriers, and specific surface area was determined. Aspirin solid dispersion capsules were prepared, the dissolution in vitro of aspirin SD and capsules were investigated. RESULTS The solubility of aspirin in aspirin SD was significantly increased compared with raw material and aspirin-carrier physical mixture. The higher the proportion of carrier, the rapider drug was dissolved. When the ratio of drug to carrier was above 1∶6, the increase of dissolution was no longer significant. Aspirin were highly dispersed in the carrier in amorphous or molecular form. Compared with raw material, the specific surface area of aspirin SD with drug-carrier ratio of 1∶6 increased by 3.2 folds; the cumulative release of aspirin in aspirin SD capsule achieved about 99.8% within 30 min. CONCLUSION The preparation technology of SD is feasible, and the quality of capsules is controllable.