In this paper, the channel estimation algorithms have been studied for the downlink of 3GPP LTE systems. Based on the reference signals of the LTE specifications, a novel channel estimation algorithm is proposed. This algorithm compares the output of the ACM (Adaptive Channel Manager) with a preset threshold. If the output of the ACM is larger than the threshold, the noise restraining filter will be employed to restrain the noises. The simulation results show that, without increasing much computational complexity, the proposed algorithm has better BER performances compared with the LTE channel estimation algorithm.