A signal-sensitizing detection method applied in distributed Brillouin optical fiber strain sensing system is propos ed.Based on coherent heterodyne detection principle,this method adopts Brillouin scattering power as the measuring parameter of strain,discarding the traditional way of constructing the Brillouin scattering spectrum with sweep frequency technique.A high frequency pulse detector with sensitizing effect is used to detect the Brillouin beat signal by envelop detection,directly transferring the Brillouin beat signal into Brillouin scattering power,which ca rries strain information and is then used to test the strain sensitization.The modulation effect of gai n response of the high frequency pulse detector would significantly increase the strain coefficient of Brillouin scattering power.Experimental results show that the strain coefficient is 0.024%/με, increased by 30 times after sensitization compared with －7.7x10－4%/με obtained by traditiona l frequency sweeping technique. The signal-sensitizing detection method also reduces detection difficulty effec tively and improves the ratio of signal to noise.The demodulated strain signal a fter sensitizing could obtain the strain measurement standard deviation of 65με,and the measurement time of just 1s at the fiber length of 24.7km.The system can efficiently meet the demand of quick and accurate measurement of strain with sim ple structure and high stability.