The invention discloses a silicon hollow beam, a silicon microaccelerometer based on the silicon hollow beam, and a preparation method thereof. The silicon hollow beam comprises a beam body produced by performing dry etching on SOI silicon chips, and the cross section of the beam body is hollow. The microaccelerometer comprises a silicon sensitive structure and a silicon substrate, which are connected into one body. The silicon sensitive structure comprises a support beam and a sensitive mass block assembly. The cross section of the support beam is the said silicon hollow beam, and the sensitive mass block assembly is fixed to a mooring anchor through the support beam. The preparation method comprises the steps of adopting the silicon sensitive structure prepared by dry etching; bonding the silicon sensitive structure and the silicon substrate having a capacitance plate assembly and a lead wire electrode by adopting silicon-silicon low stress bonding, and obtaining the microaccelerometer. The invention is advantageous in that anti-interference capability is strong, device area is small, yield rate is high, cost is low, stability is high, processing quality is high, processing robustness is good, and application scope is wide.