Photonic crystal split-beam nanocavities allow for ultra-sensitive optomechanical transductions but are degraded due to their relatively low optical quality factors. We report our recent work in designing a new type of one-dimensional photonic crystal split-beam nanocavity optimized for an ultra-high optical quality factor. The design is based on the combination of the deterministic method and hill-climbing algorithm. The latter is the simplest and most straightforward method of the local search algorithm, which provides the local maximum of the chosen quality factors. This split-beam nanocavity is made up of two mechanical uncoupled cantilever beams with Bragg mirrors patterned onto it and separated by a 75 nm air gap. Experimental results emphasize that the quality factor of the second order TE mode can be as high as 19,900. Additionally, one beam of the device is actuated in the lateral direction with the aid of a NEMS actuator and the quality factor maintains quite well even there’s a lateral offset up to 64 nm. We also apply Fano resonance to further increase the Q-factor by constructing two interfering channels. Before tuning, the original Q-factor is 60,000; it’s noteworthy that the topmost Q-factor reaches 67,000 throughout out-of-plane electrostatic force tuning. The dynamic mechanical modes of two devices is analyzed as well. Potentially promising applications, such as ultra-sensitive optomechanical torque sensor, local tuning of fano resonance, all-optical-reconfigurable filters etc, are foreseen.