The invention discloses a method for improving strain and temperature separation precision of a Brillouin optical time domain reflectometer. The method comprises the steps of firstly utilizing an Brillouin frequency shift curve and a power curve in an optical fiber which are obtained through a BOTDR to jointly modulate a strain curve and a temperature curve of the optical fiber; then reducing the fluctuation of the temperature curve and the strain curve by conducting moving average on the temperature curve and the strain curve; through the comparison of the temperature curve and the strain curve, determining an area of the temperature, the strain and joint change of the temperature and the strain in the optical fiber; afterwards by utilizing the Brillouin frequency shift curve, and according to the regions corresponding to all states, accurately solving the temperature and strain distribution in the optical fiber. According to the method for improving strain and temperature separation precision of the Brillouin optical time domain reflectometer, no additional sensing equipment or the optical fiber needs to be added, the achieving method is simple, moreover, compared with a method that temperature and strain are separated by directly utilizing the Brillouin frequency shift and power, there is no need to accurately calibrate a Brillouin power-strain coefficient and a Brillouin power-temeprature coefficient of the optical fiber, and the measurement precision is remarkably improved at the same time.