Covalent organic polymers (COPs) are designable porous organic polymers that have attracted increasing research interest and have developed as electrode materials for supercapacitors. By using an easy synthesis method, a novel phosphazene-anthraquinone-based covalent organic polymer (HD-1) was successfully designed and synthesized through a polymerization reaction between hexachlorocyclotriphosphazene (HCCP) and 2,6-diaminoanthraquinone (DAAQ) in dimethylsulphoxide (DMSO). Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption analysis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometr (EDX) and thermogravimetric analysis (TGA) were used to characterize the structure and properties of HD-1. The specific surface was calculated as 249.2 m2 g−1. The specific capacitance of HD-1 was 125.6 F g−1 at a current density of 0.5 A g−1 in a 6.0 M potassium hydroxide electrolyte. After 20 000 GCD cycles, the specific capacitance retention was about 92.8% of its initial capacitance. [ABSTRACT FROM AUTHOR]