Cavity optomechanical sensors, as a focal point at the intersection of technology and science, are pivotal for improving sensing resolution across diverse applications. This research modulates the intracavity optical field mode volume by adjusting the optical fiber coupling state to achieve controllable optomechanical coupling, leading to a strong coupling lock state. Within a chip?scale optomechanical sensor resonator system constructed from two?dimensional photonic crystals, the study successfully demonstrated the enhancement of mechanical quality factor (Q?factor) and the suppression of system noise through controllable optomechanical coupling. Experimental results indicate that in the strong optomechanical coupling lock state, the mechanical Q?factor is increased by approximately 10 times compared to the weak coupling state, and system noise is significantly reduced by about 26 dB. Moreover, the optomechanical accelerometer sensor, based on this scheme, achieves a sensitivity of 126.58 mV / g under a 6 kHz acceleration drive. This study not only validates the potential of controllable optomechanical coupling in enhancing mechanical Q?factor and reducing system noise, but also offers new perspectives for the design and application of optomechanical systems, significantly advancing the development in photonic and micro?nano mechanical systems.