Ecological stoichiometry mainly focuses on the quantitative relationships of organismal component elements and energy dynamic equilibrium across trophic levels in ecosystems. Nitrogen (N) and phosphorus (P) are essential elements for plant growth. What is the quantitative relationship between these two elements? Does the relationship between N and P vary among different plant life forms and different eco-regions? Are there intrinsic correlations between plant N and P stoichiometric patterns and its growth and functional properties? Can global changes influence the inherent N and P stoichiometry of plants? Answering these questions is major research themes of plant stoichiometry. In this paper we make a brief introduction on these questions.