Abstract: The technique of wave recording by software triggering is introduced, which is used in the monitoring system of equipment state. Through alternately storing successive triggering datas in two data blocks, it can achieve about-trigger wave recording for successive triggering. By means of labelling the priorities of the triggering sources and stopping or shielding the triggering of low priority by the triggering of high priority, it solves the problem of triggering overlap of multi software triggering sources.