Abstract: In this paper, we used the time compensation discrete Fourier transform method and discrete correlation analysis (DCDFT), Jurkevich, DCF model to analyze B band and V band periodicity of the PKS 0735+178, based on a large amount of data we have collected. We found that the variability period is about (4.33±0.41) years and the lower limits of the central black hole mass is 0.22×10⁶M_⊙.