Poly-γ-glutamic acid(γ-PGA)is a kind of extracellular macromolecule polyamide that mainly produced by microorganisms and is only made of glutamic acid units.γ-PGA is anionic，ionic adsorptive，chelating，water-absorptive，biodegradable，and biocompatibility.As a kind of fertilizer synergist in agriculture，γ-PGA can promote plant growth，increase crop yield and improve fertilizer efficiency significantly.Its totally biodegradable and biocompatibility properties make it distinguished from other chemical fertilizer synergists and have outstanding ecological and environmental advantages，which makes it has promising application prospects in agriculture in future.Currently，the theoretical basis for applying and promoting γ-PGA fertilizer is to understand its mechanism of yield-increasing and fertilizer-saving function.In order to further expand and deepen the function and contribution of γ-PGA in fertilizer industry and agriculture，this mechanism should be further studied from the perspectives of plant physiology，plant nutrition and soil nutrient cycling.At the same time，it is very needed to carry out research about synergistic effect of γ-PGA on different fertilizers，which is the theoretical basis and scientific support for developing and applying the novel γ-PGA fertilizers.