The magnetic dipole radiation model application of the classical electrodynamics theory to the description of how the pulsar's radiation is powered by the neutron star's rotational energy. But there has not been any unanimous explanation for pulsar braking process, especially explanation for why the braking index for a young pulsar is always less than the theoretical index. In this thesis, we only focus on the evolution of radius and moment of inertia. Basically, it has built a connection between the glitch phenomenon of pulsars and the physical behaviors of neutron superfluid.