The invention discloses a PTC macromolecular conductive material for a self-temperature-limited heat tracing cable. The PTC macromolecular conductive material is prepared from, by mass, 100 parts of polytetrafluoroethylene, 2-6 parts of graphene, 11-17 parts of nanosilicon dioxide, 0.2-1.5 parts of dibutyl phthalate, 0.5-2.0 part of zinc stearate, 0.2-0.8 part of salicylic p-tert-butylbenzene and0.1-0.5 part of potassium peroxodisulfate. The preparation method includes steps of feeding the quantificationally weighed polytetrafluoroethylene master batch, graphene, and nanosilicon dioxide in aheating melting device to heat and met; evenly mixing the quantificationally weighed dibutyl phthalate, zinc stearate, salicylic p-tert-butylbenzene, and potassium peroxodisulfate; then feeding to fully mix and stir; delivering to a screw extruder to extrude and immersing in cooling oil to cool to 120-150 DEG C; taking out from the cooling oil and placing in the air; cooling to room temperature. The declination rate of the overall heating performance is low.