A rotational speed sensor, a manufacturing method thereof, a driving method thereof, and an electronic device are provided. The rotational speed sensor includes liquid crystal cell, rotational speed sensing module and rotational speed determining module; rotational speed sensing module is configured to convert rotational speed into voltage signal and apply voltage signal to liquid crystal cell; and at least a part of optical signal propagation module of rotational speed determining module is located in liquid crystal cell. Spectrum drift time of optical signal propagated in optical signal propagation module is variable as refractive index of liquid crystal molecules in liquid crystal cell changes; optical signal transmitting module in rotational speed determining module transmits optical signal to optical signal propagation module; optical signal receiving module in rotational speed determining module receives optical signal propagated by optical signal propagation module and analyzes spectrum to determine rotational speed.