Footsteps, as a main kind of behavioural trait are a universally available signal. However, it remains a challenging problem to construct a robust footstep authentication system. Since, in practise, footsteps are usually accompanied with noisy and environmental sounds, it is difficult to extract stable footstep features from the mixed sounds. This study describes a novel robust footstep identification system. To extract stable features from the footsteps mixed with noisy or environmental sounds, a robust acoustic local feature extraction method is proposed. In the proposed method, the main frequency components of footsteps are determined, and then their local distributions and variations in time-frequency domain are obtained and regarded as the acoustic local features. These local features are robust to white noise, pink noise and invariant to the intensity of the footsteps. However, the conventional pattern recognition methods are not suitable for them due to that these local features are observably different from the frequently used acoustic features, and so the authors introduce a Bayesian decision classifier to implement footstep identification. Theoretical and experimental results demonstrate that this system is relatively robust to white noise, pink noise, environmental sounds and yields a better classification performance compared with the existing methods.