This paper presents a new method of analysis of bilinear systems via the single-term Walsh series (STWS). The STWS method has definite advantages over the Walsh function (WF) method and block-pulse function (BPF) method. Both the discrete values and block-pulse values of the results are obtained for any length of time and selecting any positive integer as the number of intervals. The recursive relations are simple and save both computer time and storage. Illustrative examples are presented.