A hermetically sealed X-ray framing tube with CsI photocathode is proposed to solve the problems of poor stability and low detection quantum efficiency brought by the open structure framing tube with Au photocathodes. Two microstrip photocathodes of 100 nm Au and 100 nm CsI are fabricated to compare their sensitivities under the same environmental conditions. The structure and the fabrication process of the sealed framing tube are described inthispaper. After fabrication, the sealed framing tube is tested to verify its performance. The measurement shows that exposure time of the proposed framing tube is 65 ps when gated by an ultrafast pulse with 200 ps width and -2.7 kV amplitude. At static mode, the image intensity of the CsI photocathode is 3.4 times that of the Au photocathode under the irradiation of non-monochromatic high energy X-ray source. Its static response intensity is reduced to 83% compared with the initial value after being stored in the laboratory air for 1000 h. These results indicate that the sealed framing tube with CsI photocathode can achieve higher detection efficiency and stability, and can effectively improve the quality and reliability of X-ray framing imaging.