There　are　many　advantages　for　organic　compounds　to　be　used　as　electrode　materials　of　Sodium　Ion　Batterys　(SIBs),　such　as　abundant　resources　in　nature,　lower　cost　in　price,　and　sustainable　developments.　There　is　no　effective　theoretical　method　to　predict　the　novel　organic　electrode　materials　of　sodium　ion　battery　now.　In　this　paper,　the　dispersion-corrected　hybrid　functional　theory　(HSE06-D2)　method　is　applied　to　study　an　organic　compound,　thioindigo　(SINDIG,　C16H8S2O2),　which　is　a　novel　cathode　material　of　sodium　ion　battery　based　on　the　theoretical　calculation　results.　The　two　charge/discharge　platforms＇　potentials　and　the　intermediate　state　in　the　charge/discharge　process　are　successfully　explored　with　the　theoretical　method,　which　are　verified　by　the　CV　(cyclic　voltammetry)　test　and　ex-situ　XRD　(X-ray　diffraction)　measure.　The　molecular　dynamics　(MD)　simulation　results　indicate　that　the　sodium　ions　could　diffuse　in　the　molecular　crystal　lattice　along　the　b-axis　direction.　The　energy　storage　mechanism　of　SINDIG　could　be　considered　as　sodium　ions　intercalated　into　the　molecular　crystal　lattice.　The　theoretical　method　is　proved　reliable　to　predict　other　novel　organic　electrode　materials,　and　to　explore　the　mechanism　of　the　energy　storage.　(C)　2017　Elsevier　B.V.　All　rights　reserved.