A new more practical CARS thermormetry is set up using an optical parametric oscillator (OPO). The dye laser as a broadband Stokes soucre is replaced by the tunable OPO. Theoretical analysis and experiment demonstate that the new setup is useful in the case of measuring temperature below 2200 K, and it prossesses advantages compared to the conventional dye laser, such as tunable frequency, the stable output and spectral properties, the construction of a compact CARS system and so on.