The influence of growth conditions (such as growth pressure and the flux ratio of group ID precursor) and the widths of SiO2 mask upon the thickness enhancement factors of selectively grown InGaAsP were studied in this paper. The growth rate decreased and the selectivity increased with the increasing of the growth pressure; the growth rate increased and the selectivity decreased with the increasing of the flux ratio of group III precursor. The InGaAsP bulk material with high thickness enhancement factor was grown by selective MOVPE.