The　Yb3+,　Er3+　co-doped　calcium　tungstate　materials　were　prepared.　The　temperature-sensitive　fiber　optic　probes　made　from　CaWO4:Yb3+,　Er3+　were　prepared　by　the　high-temperature　solid-phase　sintering　method.　The　XRD　lattice　structure　of　CaWO4:　Yb3+,　Er3+　was　tested.　The　fluorescence　spectra　of　the　probe　under　980nm　excitation　were　tested,　and　the　variable　temperature　profile　of　the　probe　was　analyzed　to　derive　its　two-photon　absorption　process.　The　temperature　characteristics　of　the　up-conversion　fluorescence　intensity　ratio　(FIR)　of　the　probe　in　the　temperature　range　of　303-673K　were　investigated,　and　the　results　showed　that　this　optical　fiber　probe　can　be　used　as　a　fiber　optic　temperature　sensor　with　a　linearity　of　5.8%　and　a　temperature　measurement　return　difference　of　only　1.5%;　it　was　found　that　the　temperature　characteristic　curve　of　FIR　of　this　fiber　optic　probe　was　reproducible.　These　properties　show　that　CaWO4:　Yb3+,　Er3+　is　feasible　to　be　made　into　a　fiber　optic　sensor.