Abstract: Ordinary,the dye laser is used as a stokes light source in CARS thermometry.But the dye laser has the features of bad output stabilization and big size,so we employ OPO to replace the dye laser as the stokes light source of the CARS measurement system to realize the miniaturization of the system.This paper discusses the feasibility from the theoretical and practical analysis and points out that it is feasible at the range of less 2200K.