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In order to research the cathodic thermionic emission performance difference between preparation of tungsten matrix used ungraded tungsten powder and graded tungsten powder on the micron scale, and to gain a deeper understanding of the electron emission process of the cathode surface micro-area and the cathode emission mechanism, a newly developed instrument aiming at meeting the special operation requirements of thermal dispenser cathode is used in this paper. This instrument called DUV-PEEM/TEEM combines the functions of deep ultraviolet laser photo-emission electron microscope and thermal-emission electron microscope. Thanks to the powerful functions of DUV-PEEM/TEEM, the photoelectron and thermoelectron image of prepared cathode from two tungsten powders was analyzed. The results showed that compared with the ungraded material tungsten powder, the microstructure of the tungsten matrix prepared by the graded tungsten powder is more uniform, and the closed cell ratio was reduced from 1.44% to 0.47%; the photoelectron and thermionic united imaging accurately showed that the emission of the two cathodes mainly located at the pores and active substances of pores; via thermal electron (TEEM) images, the thermal electron emission micro-area area of the cathode prepared by graded tungsten powder was larger and the distribution was more uniform than the cathode prepared by ungraded tungsten powder; and under the working condition of 1050℃, the pulse current density of the cathode prepared by graded tungsten powder was 30.79A/cm2, and the emission slope was 1.38, comprehensive analysis showed that it had more ideal intrinsic thermionic emission capability and emission uniformity, which has a certain guiding effect on understanding the cathode emission performance and improving the hot cathode preparation process.