Thermal therapy is an approach applied in cancer treatment by heating local tissue to kill the tumor cells,which requires a high sensitivity of temperature monitoring during therapy.And methods currently used in clinic like fMRI,near infrared or ultrasound for temperature measurement still have limitations on penetration depth or sensitivity.Photoacoustic temperature sensing is a newly developed temperature sensing method that has a potential to be applied in thermal therapy,which usually employs a single wavelength laser for signal generating and temperature detecting,in which accidental errors of measurement is unavoidable.In this paper,we proposed a new method of photoacoustic temperature sensing by using two wavelengths to reduce random error and increase the measurement accuracy.