We propose and experimentally validate a wavelength diversity technique combined with a passive depolarizer to improve the performance of Brillouin optical time domain reflectometry (BOTDR). This technique enables the maximization of the launch pump power and suppresses the nonlinear effects, the latter of which limits the conventional BOTDR performance. As a result, the signal-to-noise ratio (SNR) increases, thus improving the measurement accuracy for strain and temperature. In addition, considering the complexity and expensive methods required for polarization noise suppression in BOTDR system, a simple, lowcost passive depolarizer is employed to reduce the polarization noise. The experimental results show that the SNR is improved by 4.85 dB, which corresponds to 174% improvement compared to a conventional BOTDR system.