Transmission/disequilibrium test (TDT) is a commonly used method for analysis of linkage. The basis data unit used for TDT method is the case-parent triad family. Since collection of triad families could be sequentially in practical study, it is interesting to develop power-monitoring procedure for TDT testing procedure. In this paper, we use the B-Value statistic to accomplish the goal. The sequential monitoring procedure is illustrated with some examples under various genetic models.