Abstract: To investigate the synergistic effect of the drug 5-fluorouracil(5-Fu) and indomethacin(IDMC), the microspheres of poly(L-lactide) with IDMC and 5-Fu were prepared by the technique of solution-enhanced dispersion by supercritical CO₂ (SEDS), using dichloromethane/dimethyl sulfoxide as a cosolvent system. A single factor method was used to explore the best external conditions. The morphology, drug loading, particle size distribution and release profiles of 5-Fu-IDMC-PLLA microspheres were characterized, and the in vitro cell culture was designed and performed. The results indicate that 39℃, 14MPa is the preferable condition for the microspheres preparation when the ratio of the cosolvent is 30∶1. The microspheres exhibite a good spherical morphology, a particle size distribution between 0.5~ 5μm, which possess a sustained-release property and enhanced after composited with IDMC. The in vitro cell culture experiment show that the drug-loaded microspheres significantly inhibite the proliferation of A549 cell line, but the relative growth rate (RGR) of the two group of cells cultured with the microspheres before and after composition IDMC have no significant difference.