Footsteps, as a main kind of behavioral trait are a universally available signal, but it remains a challenging problem to construct an identity verification system based on them since footsteps not only reflect a person's physiological basis but also depend on the person's psychological makeup, footwear and floor. This paper describes a novel footstep identification system. In order to eliminate footwear and floor variations as limiting factors, the footstep duration and interval times are extracted from footsteps and a timing vector is obtained as the feature. In order to smooth instability of footsteps, we develop a novel pattern recognition method, in which the training procedure can be split into several parallel subprocedures, and each subprocedure only considers one class samples and involves several vector operations. So, it can be periodically retrained using the user's recent several successful identification footsteps. Then, diversification similarity degree is introduced and regarded as similarity measure, which is invariant to the change of examinee's psychological makeup between two footstep recording courses. Theoretical and experimental results show this system is relatively robust to the variations of footwear, floor, and the examinee's psychological makeup, and yields a better classification performance compared with the existing methods.