Owing to its high electromechanical coupling coefficient (k2eff>30%), the horizontal shear (SH) acoustic modes in lithium niobate (LN) single-crystal films are typically investigated to develop thin-film acoustic resonators with large electromechanical coupling and ultra-wideband acoustic filters. However, its temperature coefficient of frequency (TCF) is extremely high (>-50×10-6/℃). A high TCF not only reduces the effective bandwidth but also limits the power-management capability of the filters. Herein, we present an investigation into the optimization design of a low drift, large electromechanical coupling horizontal-shear surface acoustic wave (SH-SAW) resonator based on the X-cut LN/SiO2/Si structure using a three-dimensional periodic finite-element model. Simulation results show that when the SH-SAW propagation angle ψ is between -10° and -20°, the film thicknesses of LN and SiO2 are 0.1λ and 0.2λ (where λ is the period of the interdigital transducer) respectively, the metallization rate of the aluminum electrode (η) is 0.4, the relative thickness of the electrode is between 5% and 10%, the k2eff of the SH-SAW resonator remains at ~30%, and the TCF is less than -20×10-6/℃. Hence, the resonator is suitable for developing the next generation of low-temperature drift, ultra-wideband 5G SAW filters.