Polyphosphazenes are a novel biodegradable polymer with an inorganic backbone composed of alternating single and double covalent bond and alternating phosphorous and nitrogen atoms .Polyphosphazenes have unique properties and notable diversity of synthesis

and degradation products are nontoxic compounds such as phosphorous acid

amine

amino acid and ethanol .Tuning degradation of polyphosphazenes and controlling drug release can be achieved via changing the structures and compositions of side chain of polyphosphazenes .This review mainly summarizes the synthesis

the mode of degradation and the applications in the controlled release systems of biodegradable polyphosphazenes .