Abstract: To deal with the problem of signal estimation for Wireless Sensor Networks (WSN) in a untrustworthy environment where malicious nodes tamper the measured data, two reputation-based algorithms, that are, Reputation-based diffusion Least Mean Square (R-dLMS) algorithm and Reputation-based diffusion Normalized Least Mean Square (R-dNLMS) algorithm, are proposed. The proposed algorithms could assign the appropriate reputation value to each node according to its contribution to the whole network, and minimize the reputation value of malicious nodes to lower the impact of malicious nodes in the network. Simulation results show that the proposed algorithms can greatly improve the performance compared with the one without reputation value, and the performance of R-dNLMS algorithm has been further improved based on R-dLMS algorithm.