In this paper

a method is analyzed to calculate the backscattering optical power and frequency shift by using the electric field amplitude and frequency of the microwave signals obtained by heterodyne detection.By using this method

the fairly high power microwave signals are integrated by numerical fitting and the backscattering optical power

frequency shift and the coefficient matrix changed with the temperature and strain are calculated by using the resulted DC and AC components.The numerical results show that the demodulation precisions of the temperature and strain are 1℃ and 100 με respectively

yet restrained by certain sampling frequencies.