To　investigate　systematically　how　the　temperature　effect　influences　the　measurement　accuracy　of　a　hydrostatic　leveling　system　(HLS),　ambient-temperature　and　temperature-gradient　test　platforms　were　built　in　the　laboratory.　The　temperature　of　each　measuring　point　of　the　HLS　was　collected　by　a　high-precision　temperature　sensor,　and　the　influences　of　the　ambient　temperature　T-A,　temperature　gradient　T-G,　heating/cooling　rate,　communicating-pipe　expansion　coefficient,　and　measuring-point　distance　D-test　on　the　HLS　measurement　accuracy　were　analyzed　quantitatively.　The　results　show　that　the　error　of　the　two-HLS　setup　was　caused　by　the　expansion　of　the　communicating　pipe　and　the　liquid　between　the　datum　point　and　the　measuring　point　both　under　ambient-temperature　and　temperature-gradient　conditions.　The　relative　ambient-temperature　influence　coefficient　Delta　P　and　temperature　gradient　influence　coefficient　Delta　Pt-G,　respectively,　had　a　linear　correlation　with　the　difference　between　the　expansion　coefficients　of　the　communicating　liquid　and　pipe　(gamma(di)　-　gamma(pi)).　Moreover,　Delta　Pt-A　and　Delta　Pt-G　had　a　negative　power　relationship　with　D-test　for　given　communicating　pipe　and　liquid.　A　temperature-modified　model　was　developed　theoretically　based　on　test　results,　and　its　reliability　was　verified　via　on-site　tests.