Abstract: A system for detecting the burn degree of skin comprises a laser source for generating a laser, a light-splitting device for splitting the laser into a pump beam and a probe beam, a modulation device positioned on the optical path of the pump beam, a sampling device positioned between the light-splitting device and the modulation device, a terahertz pulse emitter for generating terahertz pulses by the irradiating of the pump beam, a terahertz pulse detector for detecting the terahertz pulse reflected by a sample, a current detector electrically connected to the terahertz pulse detector, and a phase lock-in amplifier electrically connected to the current detector. The terahertz pulse emitter includes a plurality of photoconductive antennas positioned in an array manner, and the system further comprises a first fiber coupler for transmitting the pump beam from the modulation device to the photoconductive antennas of the terahertz pulse emitter.