Taking a coupled system of identical HR neurons for instance, we explored how to actualize its desynchronization by adding a sinusoidal pacemaker to the system. It was discovered that the pacemaker with a sinusoidal signal could weaken the synchronization of the system and also change the modes of the neurons’ sparks. Therefore, the extents of the system’s desynchronization were classified. Then, the indexes for measuring the level of the desynchronization were designed and several homologous simulations were done. The results showthat,in a certain range of parameters, the level of the system’s desynchronization is far more sensitive to coupling coefficient between the two neurons than the controlling coefficient of the pacemaker.