In this paper, we have analyzed Brillouin frequency shift (BFS) in single mode silica optical fiber. The BFS is analyzed in conventional Brillouin optical time domain analysis (BOTDA) at operating wavelength of 1550 nm by a pump-probe technique. The effects of strain and temperature on BFS are fully characterized. We found that, the BFS change of 0.06 MHz/µ-strain and 1.26 MHz/oC, respectively. The BFS changes in Brillouin gain and Brillouin loss mechanism have been analyzed. In addition, we also presented Brillouin linewidth and peak gain variations of Brillouin gain spectrum with various temperature and strain values. The results demonstrate, the BFS have a strong linear relationship with strain and temperature along the sensing fiber.