Orthogonal Frequency Division Multiplexing(OFDM)is a kind of transmission techniques with high frequency efficiency,which will be widely used in next-generation wireless communication systems.In this paper,pilot-based channel estimation for IEEE 802.16a OFDM system is studied.By comparing the performance of LS(least squares)estimator and Linear Minimum Mean-Square Error(LMMSE)estimator using Preamble 1 and Preamble 2 suggested by IEEE 802.16a standard in slow fading channel,we propose that Preamble 1 can be used in small multipath delay spread channel and Preamble 2 can be used in large multipath delay spread channel.Considering the tradeoff between performance and complexity,the LS estimator is suggested.