Inorganic polyphosphate (Poly P), is a linear chain of tens or many hundreds of phosphate residuals linked by high-energy phosphoanhydride bonds, and widely exist in prokaryotes and eukaryotes. Many researches demonstrated that Poly P can affect the virulence of bacteria, and help bacteria to survive in nutrient-deficient environment. Poly P has been identified to be related with the RNA transcription in nucleolus of eukaryotes. Poly P can also promote cell differentiation and modulate inflammatory response. Additionally, Poly P is related to mineralization and demineralization vertebrate bones. Poly P is the activator of mitochondrial permeability transition pore. This review is aim to summarize the impacts of Poly P to microorganism or mammal, and get more attention for the importance of Poly P.