Film Bulk Acoustic Resonator(FBAR) can be applied in oscillating circuits to transform humility and pressure of atmosphere into frequency signal. Three kinds of oscillating circuits are designed for the FBAR whose quality factor is low: Pierce oscillator, ring oscillator, improved cross-coupled oscillator. Different methods are adopted in the three kinds of oscillators to optimize phase noise and power dissipation. The quality factor of the FBAR is 205.5, and SMIC 0.18 μm CMOS is utilized. The power dissipation of three kinds of oscillators is respectively 26.3 mW, 0.382 mW, 4.32 mW, and the phases are respectively -111 dBc/Hz, -152 dBc/Hz, -126 dBc/Hz at a 1 MHz offset. The improved cross-coupled oscillator can meet the requirement of precise detector.