Defect-related deep-level traps in two-step annealed Czochralski-grown silicon (Cz-Si) wafers are examined by the photoluminescence (PL) method. As interstitial oxygen reduction increases after the annealing, the deep-level emissions labeled by the D1 and D2 lines become stronger in the PL spectra at 4.2 K. The band-edge PL intensity at room temperature decreases with an increase in the D-line emission. The decay-time curve of the band-edge emission is successfully measured under the same excitation condition as the band-edge PL intensity measurement using an instrument we developed. Using this decay-time curve method, the band-edge PL intensity is correlated to the carrier lifetime for the two-step annealed Cz-Si wafers.