The invention is applicable to the technical field of a sensor, and provides a micro-nanofiber Michelson interferometric hydrogen sensor. The micro-nanofiber Michelson interferometric hydrogen sensor comprises a broadband light source unit, a coupling unit, a sensor light path, a reference light path, and a demodulating unit; the broadband light source unit is used for generating a broadband light with preset width and sending to the coupling unit, and the coupling unit is used for performing light splitting on the broadband light, sending the split sensor detecting light to the sensing light path and sending a reference light acquired by splitting to the reference light path; the sensing light path is used for reflecting the sensing detecting light, and sending the sensing detection reflecting light acquired by reflection to the coupling unit; the reference light path is used for reflecting the reference light, and sending the reference reflecting light acquired by reflection to the coupling unit; the coupling unit is further used for combining the sensing detection reflecting light with the reference reflecting light, and sending an interference light acquired by combining to the demodulating unit; the demodulating unit is used for detecting and demodulating the interference light, and acquiring an interference spectrum. The sensor provided by the embodiment is simple in sensor preparation and good in processing repeatability.