High quality single crystals of Tm,Ho:GdScO₃ were grown using the Czochralski method. The transmittance spectra of (100), (010) and (001) planes of the crystal were measured at room temperature, and the absorption coefficient and absorption cross-section of the crystal were calculated. The transition intensity parameters Ω_tfor Tm³⁺ and Ho³⁺ co-doped crystal were fitted using the product of dopant concentration N and absorption oscillator intensity f was fitted as a parameter, and the spectral parameters such as spontaneous radiation transition probability, radiative lifetime and fluorescence branching ratio were also calculated. The results show that, the Tm,Ho:GdScO₃ crystal has good luminescence performance, and the calculated spectral parameters provide data reference for the study of its laser output performance.