Microwave-assisted extraction of rosmarinic acid in perilla frutescens leaves was optimized by response surface method. The optimal process conditions were as follows, the microwave power 560W, processing time 4.5min, solid-liquid ratio 1∶33 (1g sdid in 33mL solvent). Under the optimal conditions, the rosmarinic acid yield reached 2.55g/mg. Compared with conventional extraction process of rosmarinic acid in perilla frutescens leaves, microwave-assisted extraction process is feasible.