A novel method for exciting and detecting vibration of silicon microresonator sensors is presented. A single laser diode is used for excitation and detection, and an all-fiber Fizeau interferometer is applied. The displacement signal of microresonator is demodulated from the interference signal, which is modified with the intensity change of the laser diode. The Bessel function ratio method is used to enlarge the measurement range. And some working parameters need not be measured. Using this method the resonance frequency about 8.81 kHz and the tested cantilever amplitude at resonance about 135 nm were obtained. The experimental results are consistent with those of other method, so practicability of the new method is proved.