Due to the impurity gettering effect, the control of oxygen-related defects is still key technology for large size singel crystal growing. And to know the exact behavior of lattice defects is very important to solve many process problems which occurred during device fabrication. We have investigated the defect density distribution of oxygen-containing single crystal Si wafer(Xz-Si) by means of positron lifetimes and dopplar broadening method. From the experimentally obtained spectra, we obtained the mean-lifetimes of positrons and then compared with the S-parameters from doppler broadening measurement. We could confirm that the tendency of variation for the mean-lifetime with respect to positions on wafer is well agreement with that of S-parameters. Hence, we have found that the concentrations of oxygen-related defects at the range of edge are larger than those at the center ranges.