The invention relates to a temperature sensor based on surface plasmon, and belongs to the field of temperature sensing and solves the problems of low sensitivity and difficulty in integration of an existing temperature sensor. The temperature sensor comprises a white light source, a single mode fiber I, a grating, a metal-medium-metal resonant structure, a single mode fiber II and a spectrograph, wherein white light emitted by the white light source is coupled by the single mode fiber I and the grating sequentially, then is incident to the metal-medium-metal resonant structure and generates resonance and interference in the metal-medium-metal resonant structure, so as to form Fano linear light waves to be emitted, and the Fano linear light waves emitted by the metal-medium-metal resonant structure are coupled by the single mode fiber II and then enter an entrance slit of the spectrograph. The waveform of the Fano linear light waves changes as the external temperature changes, and detailed data of the waveform change can be obtained by the spectrograph. The temperature sensor based on the surface plasmon is especially suitable for temperature sensing.