N or P availability constrains plant growth in tropical and subtropical regions, and may influence plant hydraulic system that mediated forest vulnerability to drought. Although the effects of N/P availability on plant hydraulic traits have drawn much attention, most studies neglected the hydraulic failure threshold, and were limited to single species using fertilization experiments. This study aimed to fill this gap by examining how variation in the relative availability of N/P, as reflected by foliar N:P ratios, influences plant hydraulic failure threshold across a broad range of species by collecting published data and doing field experiments. The results demonstrated that increasing P availability would decrease the hydraulic safety margin (increase hydraulic failure risk) by regulating the leaf area: stem area ratio and vessel wall reinforcement. Forest drought-induced mortality was predicted to increase with increasing temperature; however, this study suggests N deposition-driven decreases in P availability would potentially alleviate this trend.