Abstract: A novel method was put forward to measure the line width of stimulated Brillouin scattering(SBS) in water based on time-domain Fourier transform. The pulse duration and line width of SBS was studied over a temperature range of 5℃ to 40℃. Firstly, the pulse duration is measured with an oscilloscope, then the pulse duration at different temperature was obtained through Fourier transform and linewidth alignment. Experimental results and estimation of statistical error show that, this method possesses higher measurement accuracy(maximum error of measurement is less than 3.5%) and is a simple and feasible approach.