Abstract
Fermion masses and mixing angles are studied in an SUSY SO(10)×Δ(48)×U(1) model with small tanβ. Thirteen parameters involving masses and mixing angles in the quark and charged lepton sector are successfully predicted by a single Yukawa coupling and three ratios of VEV's caused by necessary symmetry breaking. Ten relations among the low energy parameters have been found with four of them free from renormalization modifications. They could be tested directly by low energy experiments.