When the ferrofluid is magnetized with biasing field, it's dielectric characteristics shows a magnetoelectric directive effect, i.e., the dielectric constant depend on not only the magnetic field, but also the relativf direction between the electric field and the magnetic field.In experiments, it has been observed that the magnetic particles in the ferrofluid are of spherical shape, and when magnetized with biasing field, they take a long-chain type distribution.In this paper, we analyze experimental results mentioned above and explain the magne-toelectric directive effects with long-chain model. The theoretical results are in agreement with experimental work.