A　pneumatic　gravity　compensation　system　is　typically　nonlinear　in　behavior.　It　is　difficult　to　establish　an　accurate　mathematical　model　for　it,　and　it　is　particularly　difficult　to　realize　high-precision　pressure　control.　A　pneumatic　gravity　compensation　system　driven　by　a　frictionless　cylinder　is　built.　Considering　that　the　traditional　model-free　adaptive　control　is　slow　for　pseudo-gradient　identification,　an　improved　model-free　adaptive　control　is　proposed　to　predict　the　changes　in　the　pseudo　gradient　and　accelerate　the　process　of　pseudo　gradient　identification.　The　static　and　dynamic　gravity　compensation　of　the　pneumatic　gravity　compensation　system　is　realized.　Finally,　the　experimental　results　show　that　the　steady-error　of　step　response　of　the　improved　model-free　adaptive　controller　is　less　than　200　Pa,　and　the　rise　time　is　approximately　13　seconds.　The　sinusoidal　tracking　error　(0.04　Hz)　is　approximately　1.94　KPa.　©　2020　Fuji　Technology　Press.　All　rights　reserved.