Abstract: The Suspended Microchannel Resonator has extensive applications in the sensor field due to its micro-size and high sensitivity. It can be used to measure physical quantities such as weak force values, mass, density, and fluid viscosity. In this study, considering the impact of fluid motion on the cantilever beam's mechanics, a fluid - structure coupling equation is formulated and numerically solved. The effects of fluid density and flow conditions on the cantilever - beam resonator's resonant frequency and deformation are explored. Results show that rising fluid density reduces the resonant frequency and increases deformation. There is a linear link between the Reynolds number and the resonant frequency. As the Reynolds number grows, the frequency error coefficient increases, affecting measurement accuracy. These findings provide theoretical support for improving the measurement accuracy and sensitivity of microchannel resonators.