In this study, CaMoO4: 4 : Eu3+ 3+ phosphors with molar concentrations of 0.01 %, 0.03 %, and 0.1 % were synthesized via the hydrothermal process. The variable temperature PL spectra demonstrated a pronounced decline in the luminescence of MoO42- 4 2- with the temperature rising, suggestive of typical thermal quenching behavior, whereas the luminescence of Eu3+ 3+ showcased an emerging trend characterized by an initial increase followed by a decline. This phenomenon was attributed to the intensified energy transfer effect from MoO42- 4 2- to Eu3+ 3+ as the temperature increased. The thermal quenching trends between MoO42- 4 2- and Eu3+ 3+ exhibited distinct differences, leading to the acquisition of high relative sensitivity when utilizing the FIR of MoO42- 4 2- and Eu3+ 3+ for temperature sensing. It was found in the experiment that samples with higher Eu3+ 3+ doping concentrations exhibited higher S r . In the CaMoO4: 4 : 0.1 % Eu3+ 3+ sample, the S r-max reached 3.19% K- 1 at 303 K, which was an excellent value among inorganic materials. The findings of this paper indicate the potential application of CaMoO4: 4 : Eu3+ 3+ phosphors for optical thermometry.