A convenient 3ω method was developed to measure the thermal conductivity of multiwalled carbon nanotube/polypropylene （MWCNT/PP） composite，in which the metal strip heater was substituted for a platinum wire，and the commercial lock-in amplifier was replaced by a Labview-based virtual measurement system. The experimental result showed that，the thermal conductivity of multiwalled carbon nanotube/styrene-butadiene rubber/polypropylene （MWCNT/SBR/PP） ternary composite varied slightly with MWCNT/SBR powder loading; the thermal conductivity of MWCNT/PP composite increased with the increasing MWCNT loading; the composite thermal conductivity was far less than that expected from the law of mixtures，but in good agreement with the effective medium approach by incorporating the thermal interfacial resistance between the MWCNT and the surrounding polymer matrix.