Objective：To investigate the in vitro release mechanism of rifapentine-loaded poly（lactic-co-glycolic acid）（PLGA） microspheres. Methods：Rifapentine-loaded PLGA microspheres were prepared by the emulsification-solvent evaporation method. The in vitro release tests were carried out in phosphate buffer solution（0.2 mol/L，pH7.4），and the in vitro release profiles were prescribed by the zero-level equation，one-level equation and Higuchi equation，respectively. Results：Rifapentine-loaded PLGA microspheres were successfully prepared with drug loading of （8.04±0.29）%，（17.16±0.40）% and （23.93±0.48）%（F=1 195.325，P=0.000）. The microspheres were spherical particles with good dispersion. Rifapentine was evenly distributed in the PLGA matrix. The drug release was faster during the first two days and the cumulative drug releases of the three rifapentine-loaded PLGA microspheres were （9.07±0.11）%，（13.33±0.04）% and （15.5±0.09）%（F=4 414.474，P=0.000），which slowed down from the third day. The total cumulative drug releases were （72.10±0.26）%，（80.22±0.56）% and （78.60 ± 0.63）%（F=212.916，P=0.000）. The correlation coefficients of the Higuchi equation were closer to 1 among that of the three fitting equations. Conclusion：Rifapentine-loaded PLGA microspheres exhibit an initial burst followed by a period of slow release in vitro，and the release profiles is more consistent with the Higuchi equation.