In this paper, a scheme for symbol timing estimation and delay spread estimation using subblock correlation is proposed in the OFDM systems. The subblock correlation between the cyclic prefix and data symbol is applied to estimate symbol timing and the length of delay spread. Under a multipath fading channel referred to the OFDM multipath channel model in the standard of IEEE 802.11a/g WLAN, the results show that performance with the proposed scheme is better than that with Beek's scheme. In addition, the length of the delay spread could be estimated in the proposed scheme. Hence, in order to increase the bandwidth efficiency, the length of cyclic prefix could be adaptively assigned in the OFDM system.