In the past few decades, achieving room-temperature superconductivity has become an unremitting pursuit of scientists. Guided by the “chemical precompression” theory, hydrogen-rich compounds have emerged as the main candidates for high-temperature superconductors, positioning them at the forefront of superconducting materials research. Extensive computational studies have identified numerous binary hydrides with predicted superconducting transition temperatures (T_c) exceeding 200 K, such as CaH₆, H₃S, MgH₆, YH₆, YH₉, YH₁₀, and LaH₁₀. Significantly, the high-T_c super-conductivities of H₃S, LaH₁₀, CaH₆, YH₆, YH₉ have been experimentally confirmed. Compared with binary hydrides, ternary hydrides offer more diverse chemical compositions and structures, potentially leading to enhanced properties. Zhang et al. [Zhang Z, Cui T, Hutcheon M J, et al. 2022 Phys. Rev. Lett. 128 047001] theoretically designed a series of AXH₈-type (A = Sc, Ca, Y, Sr, La, Ba; X = Be, B, Al) ternary hydrides with “fluorite-type” backbone, which were predicted to have high-T_c values under moderate pressure. Among those ternary hydrides, LaBeH₈ has been experimentally confirmed to achieve a T_c value of 110 K at 80 GPa. The T_c values of ternary clathrate hydrides of Li₂MgH₁₆ and Li₂NaH₁₇ have been predicted to greatly exceed the room temperature, while the required stabilization pressures all exceeded 200 GPa. Xie et al. [Xie H, Duan D F, Shao Z J, et al. 2019 J. Phys. Condens. Matter. 31 245404] and Liang et al. [Liang X W, Bergara A, Wang L Y, et al. 2019Phys. Rev. B 99 100505(R) ] independently predicted CaYH₁₂ compounds with $ Pm\bar 3m $ and $ Fd\bar 3m $ space groups, both of which exhibited high-T_c above 200 K at about 200 GPa. Other ternary hydrides, such as La-B-H, K-B-H, La-Ce-H, and Y-Ce-H, have also been extensively investigated. At current stage, a major focus of superconducting hydrides is to achieve high-temperature superconductivity at lower pressures. In this study, taking $ Pm\bar 3m $ (CaYH₁₂) as a representative, we systematically investigate the effects of electron and hole doping on the dynamical stability and superconductivity in ternary hydride by first-principal calculations. The $ Pm\bar 3m $ (CaYH₁₂) exhibits a T_c value of 218 K at 200 GPa, which is consistent with that reported previously. When decompressing to below 180 GPa, imaginary phonons emerge. The analysis of doping simulations demonstrates that the electron doping exacerbates the softening of the imaginary phonons, whereas hole doping eliminates the imaginary frequencies. At the pressures of 130, 100 and 70 GPa, the $ Pm\bar 3m $ (CaYH₁₂) phase can be stabilized by hole doping at the concentrations of 0.9, 0.8, and 1.1 e/cell, respectively. Further electron-phonon coupling calculations show that the T_c values of $ Pm\bar 3m $ (CaYH₁₂) at 130, 100 and 70 GPa are 194, 209, and 194 K at the corresponding doping level, which are only 10–20 K less than the T_c at 200 GPa. At the pressure of 70 GPa, T_c slightly decreases to 189 K at a doping level of 1.2 e/cell, primarily due to the reduced ω_log compared with that in the case of 1.1 e/cell. And the enhanced λ at 1.2 e/cell is mainly contributed by the average electron-phonon coupling matrix element $ \langle {I^2}\rangle $ and average phonon frequency $ {\langle {\omega ^2}\rangle ^{1/2}} $, rather than the electronic density of states at the Fermi level N(ε_F). These results indicate that hole doping represents a promising and effective strategy for optimizing the superconductivity of $ Pm\bar 3m $ (CaYH₁₂) by maintaining high-T_c at low pressures. Our study paves an avenue for realizing high-temperature superconductors at low pressure.