Aligned carbon nanotubes(CNTs)/epoxy resin(EP) composites were prepared under a low magnetic field (B<500mT) induction. The effect of different magnetic fields on the electrical and dielectrical properties of composites was investigated. The results show that the CNTs are aligned with rod-like aggregations instead of single CNTs when the magnetic field direction is vertical to the casting direction of samples, then electric conductivity, permittivity, dielectric loss of the composite are improved. And a larger magnetic field intensity and a bigger mould capacity can help the effect of magnetic field induction. However the CNTs are seriously aggregated and the electrical properties of composites change worse when the magnetic field direction is parallel to the casting direction of samples.