We study the heat generation in ferromagnet-quantum dot-ferromagnet system by the non-equilibrium Green's functions method. Heat generation under the influence of ferromagnet leads is very different compared with a system with normal metal leads. The significant effects in heat generation are caused by the polarization angle associated with the orientation of polarized magnetic moment of electron in the ferromagnetic terminals. From the study of heat generation versus source drain bias (Q-eV) curves, we find that the heat generation decreases as increases from 0 to 0.7. The heat generation versus gate voltage (Q-eV(g)) curves also display interesting behavior with increasing polarization angle . Meanwhile, heat generation is influenced by the relative angle of magnetic moment in the ferromagnetic leads. These results will provide theories to this quantum dot system as a new material of spintronics.