This　work　investigates　an　electrostatically-actuated　vibrating　beam　micro/nano-gyroscope　made　of　nanocrystalline　silicon　material.　The　comprehensive　size-dependent　micro/nanogyroscope　model　is　developed　by　couple　stress　and　surface　elasticity　theories.　Then,　considering　the　effects　of　intermolecular　forces　(Casimir　force　and　van　der　Waals　force)　and　surface　stress　residual,　an　in-depth　investigation　was　conducted　on　the　performance　of　the　micro/nanogyroscope.　The　calculation　results　display　that　the　maximum　static　deflection,　pull-in　voltage　and　natural　frequency　change　obviously　with　the　increase　of　surface　stress　residual　as　the　scale　varies　from　micrometer　to　nanoscale.　However,　the　effect　of　intermolecular　forces　on　the　performance　of　gyroscopes　is　exactly　the　opposite,　which　improves　the　prediction　of　system　structural　softening　deformation　phenomenon.　Considering　the　influence　of　the　Casimir　and　van　der　Waals　forces　in　micro/nano　gyroscopic　system　will　help　gyroscopes　to　obtain　reliability　and　functionality　sensitivity,　increase　the　accuracy　of　predicting　static　deformation,　natural　frequency　and　differential　frequency.　Moreover,　a　frequency-domain　method　using　the　difference　between　the　two　vibration　natural　frequencies　is　studied,　with　changing　the　scale　of　the　gyroscope　under　the　effect　of　the　intermolecular　forces.　The　numerical　simulations　exhibit　that　when　considering　smaller　structure　sizes　of　the　gyroscope,　strong　coupling　occurs　between　the　intermolecular　forces　and　surface　stress　residual,　which　is　helpful　for　the　design　of　micro/nano　gyroscopes.　©　2024　Elsevier　Masson　SAS