In this study, multiferroic BiFeO3 particles with size of ∼ 50 nm and good crystallinity were prepared via a simple sol–gel method and annealing. And the volatile organic compounds (VOCs) sensing properties of BiFeO3 sensor were measured under both traditional thermal excitation and synergetic thermal-magnetic excitation. In particular, auxiliary magnetic field was first introduced into testing environment. The results shows that the optimum operating temperature of the sensor decreases 10℃ by introducing magnetic field, and the sensor shows three times faster response speed and diverse selectivity with best response to n-butanol under thermal excitation while butanone under thermal-magnetic excitation. In addition, the sensor has response value of 1.25 to 1 ppm n-butanol, indicating the possibility of detecting low concentration of toxic gases. The effect of magnetic field on multiferroic BiFeO3 sensor can be divided into three aspects: decrease of defects on domain wall, excitation of testing gas molecules with asymmetry electron cloud distributions and activation of surface-absorbed oxygen species with unpaired electrons.