The performance of OFDM systems may be degraded when intersymbol interference (ISI) chan- nels have spectral nulls. Recently, the precoded OFDM was proposed to combat this problem. How- ever, due to inserting (M-K) zeros between each two sets of K consecutive information symbols, the average transmitting power of the precoded OFDM system reduces by 10log10 (M/K) dB com- pared with the conventional OFDM system. Under the same points inverse fast Fourier transformation (IFFT), the precoded OFDM system has a higher peak-to-average power ratio (PAPR) compared with the conventional OFDM system. This paper proposes a novel precoded BPSK-OFDM system based on Haar wavelet transformation. The Haar wavelet transformation operating decomposition over the vector information symbols produced by a precoder shows that half of the information symbols are zeros and the rest are either √2 or -√2.Then ,we have the peak power and PAPR reduced by 10log102≈3dB at most compared with the precoded OFDM system. Finally, we compare PAPR of the proposed OFDM system with the precoded OFDM and the conventional OFDM system.