The temporal stability of a plant community in a native grassland ecosystem is affected substantially by soil nitrogen (N) and phosphorus (P) enrichment. However, the interactions between N and P inputs and arbuscular mycorrhizal fungi (AMF) and their effects on the temporal stability of plant productivity have not yet been clarified. In this study, we combined a three-year in situ field experiment with a worldwide meta-analysis to assess the effects of soil fertilisation and AMF on the temporal stability of plant productivity. The addition of P decreased the stability of plant productivity as the standard deviation of plant productivity was increased directly and the temporal stability of C3 grasses was decreased. However, there was no relationship between species richness and the stability, and of plant productivity, rather the stability of the dominant functional group and asynchrony among functional groups were the main drivers changing the stability of change in plant productivity. In both the site-specific experimental data analysis and worldwide meta-analysis, the negative effects of P addition overrode the positive effects of AMF on the temporal stability of plant communities. Overall, our study highlights the importance of soil nutrient availability over AMF in terms of shaping the temporal stability of a plant community. Our results also suggest that anthropogenic soil nutrient enrichment might reduce the temporal stability of plant communities in grassland environments regardless of the existence of AMF.