The field emission electron source has a wide range of application value in the field of vacuum electronics, and the realization of the uniformity and patterning of the in-situ growth of the emitter material is the key technology. The traditional patterning process is complicated and the pattern has not been carefully designed, resulting in uneven electric field distribution. This paper uses ANSYS Maxwell 16.0 simulation software to study the law of electron motion trajectory, and proposes a new idea of the effective emission size of the graphical emitter array and the cathode structure of the optimal array spacing to improve the field emission performance. The simulation results show that when the array spacing d is 200 μm, the electric field distribution in the central area of the patterned array is flat, and the surrounding area of the array rises abruptly. This is mainly due to the fact that the edge part of the array exhibits the characteristics of a needle tip more than the central part of the array. When d is smaller, the field strength of the edge area between the unit arrays is superimposed, and a field strength superimposition area appears. When d slowly increases, the edge superposition effect of the field strength is weakened, and the electric field shielding effect is also weakened. Therefore, when d is larger (400 μm), the field strength of the cathode surface tends to be flat, because the edge superposition effect of the field strength and the electric field shielding effect are balanced. However, as d increases to a certain extent, when the array spacing is 600 μm, the center position of the cell array plane can be relatively far away, the field emission of the cell array is relatively independent, and the electron emission has a neutral area. It can be seen that when d is selected at a moderate value, the superposition effect of the field strength at the edge of the array is weakened, and there will be no blind areas in the surrounding electric field, and the electric field basically achieves a uniform distribution. Subsequently, according to the simulation results, the patterned seed layer is accurately positioned by inkjet printing, and then the ZnO nanorod array is hydrothermally grown. Field emission test results show that as d increases, the turn-on field strength E_on decreases from 2.95 V/μm at 200 μm to 0.57 V/μm at 400 μm, and further changes to 2.26 V/μm at 600 μm. The enhancement factor b increases first and then decreases as d increases from 200 μm to 600 μm. This is consistent with the simulation results, that is, when the effective emission size of the ZnO cathode array is 200 μm, when d is 400 μm, the field emission performance is optimal, and its turn-on field is 0.57 V/μm, and the field emission enhancement factor is 32 179. Combining the high efficiency of graphic design and inkjet printing, it is expected to realize a high-performance field emission electron source.