A passive radio frequency identification (RFID) chip with a protection function against high-intensity electromagnetic fields includes an antenna for receiving electromagnetic waves generated by an RFID reader and generating AC electrical signals to output to a power unit at an output of the antenna; an input/output circuit; a logic circuit; the power unit for rectifying the AC electrical signals into DC (direct current) voltage and outputting the DC voltage to the logic circuit and the input/output circuit at an output of the power unit; a variable-capacitance diode including an anode connected with the output of the antenna and a cathode connected to ground; and a diode including an anode connected with the output of the power unit and a cathode connected with the output of the antenna. The passive RFID chip prevents the inner logic circuit and the input/output circuit from being damaged when receives high-intensity electromagnetic waves.