The frequency dispersion of the surface acoustic wave (SAW) filters prepared by Piezoelectric-on-Insulator (POI) wafer under conventional photolithography process is investigated in this paper. The results show that the chromatism of the piezoelectric single crystal thin film is the fundamental reason for the deterioration of frequency consistency. In this work, we used bottom anti-reflection coating (BARC) technology to suppress the reflection from the wafer and partitioned the exposure regions to compensate different color blocks. Both the ways can effectively improve the frequency consistency of the SAW filters. The proportion of maximum device quantity in 2 MHz is improved from 48.81% in conventional exposure process to 53.57% in BARC technology and 70.24% in partition exposure progress.