Some studies have shown that low achieving pupils, especially low achievers in math report more prospective memory (PM) problems than high achievers. To explore how to improve their PM performance, and how target salience and task importance of PM affect PM performance in low achievers in math, the effects of target salience and task importance on PM and prospective memory were compared between low and high achieving pupils in math in the present study. Target salience (PM tasks with salient target vs. PM tasks with non-salient target) was manipulated as a within subject factor, and task importance of PM (importance emphasized vs. no importance emphasized) and achieving group (low vs. high achieving pupils in math) as between subject factors. Furthermore, to examine prospective interference to the ongoing task, every participants completed a set of baseline tasks without PM. The results suggest that high achieving pupils outperformed low achieving pupils in PM tasks. Salient targets improved PM performance. But emphasizing PM importance improved PM accuracy only in non-salient PM condition. According to the results, it is important to help low achievers to establish a salient target for their PM tasks. If the target can’t be salient, then emphasizing the importance of the PM tasks.