An experiment on two prepared Fe-Co-Ni MRFs (Magneto Rheological Fluids) was conducted through a homemade device. Then, the electrical and thermal conductivities of the two MRFs wereare analyzed and compared with those of the Fe-Co-Ni magnetic powder itself. The results show that the magnetic field causes the electrical and thermal conductivities of the Fe-Co-Ni MRFs and magnetic powder to change greatly, and that, when the magnetic field intensity increases within 0~0.92T, the resistance of the Fe-Co-Ni magnetic powder decreases by two-to-three orders of magnitude with a significant increase in thermal conductivity increase which is from 4W/(m2•K) to 13.2W/(m2•K), and the thermal conductivities of the two MRFs also increase.