For the standard single-mode optical-fiber,the frequency shift of Brillouin scattering light is the function of the temperature or strain. So,the temperature or strain of the optical-fiber can be obtained,when Brillouin frequency shift is able to be detected. Brillouin optical time-domain analyzer (BOTDA) is suitable for long-distance distributed sensing,but the stimulated Brillouin scattering is polarization related,which makes it hard to stably detect the Brillouin optical frequency shift. A method named with the orthogonal polarization control is adopted to reduce the effect of the optical-polarization-related problem. A laboratorial system of 25 km distributed Brillouin optical time-domain analyzer is achieved,with 2 ℃ in temperature resolution,30 με in strain resolution,and 5 m in spatial resolution.