The invention discloses a micro-mechanical space optical modulator, belonging to the fields of micro-opto-electric-mechanic system technology and communication technology. The optical modulator comprises an optical grating with adjustable period and a micro-torsion mirror, wherein the optical grating with the adjustable period sequentially comprises an optical grating device layer 6 and an optical grating insulating layer 5 from top to bottom; the micro-torsion mirror sequentially comprises a micro-torsion mirror device layer 3, a micro-torsion mirror insulating layer 2 and a micro-torsion mirror base layer 1; and the optical grating with the adjustable period is combined with the micro-torsion mirror into a whole by bonding through the optical grating insulating layer 5 and the micro-torsion mirror device layer 3. The micro-mechanical space optical modulator has the beneficial effects that the micro-torsion mirror is integrated with the optical grating with the adjustable period, so that the functions of an optical switch and an optical attenuator are realized at the same time; the selection of a plurality of optical channels can be realized by the torsion of the micro-torsion mirror, so that the number of light path switching elements can be reduced, and the stability and the response speed of the light path can be improved; and the micro-mechanical space optical modulator can accurately control the optical attenuation when realizing the optical attenuation function.