Good sealing conditions are key to the preservation of helium resources, which play a crucial role in evaluating the exploration potential of helium resources in a certain area. Currently, the research on the capping characteristics of the helium reservoir is still in its infancy. In this paper, the characteristics of capping and sealing of helium reservoir are studied.Methods: In this paper, the capping mechanism and the relationship between macroscopic and microscopic characteristics of the capping layer and the sealing effect of helium were investigated by summarizing the capping characteristics of helium reservoirs all over the world. After that, the capping and sealing characteristics of the helium reservoir in Tarim Basin are analyzed.Results: The sealing mechanism of helium reservoir mainly includes three sealing mechanisms: physical property sealing, pressure sealing and concentration sealing. The sealing effect of cap rock on helium reservoir is affected by a series of microscopic characteristics (porosity, permeability, breakthrough pressure, median radius) and macroscopic characteristics (lithology, thickness, diagenesis, continuity, tectonics). The sealing ability of cap rock on helium gas is also different due to the different carrier gas types of helium reservoir. The sealing conditions of Hetianhe Block and Yakela Block are more favorable to the Gucheng Block, conventional methods for evaluating capping conditions of hydrocarbon reservoirs are not fully applicable to the assessment of capping conditions of helium resources.Conclusions: According to the relationship between the cap rock characteristics and the sealing efficiency of the helium reservoir summarized in this paper, the cap conditions of the helium reservoir can be preliminarily evaluated. The research on the method of accurately analyzing the cap conditions of the helium reservoir is still in the exploration stage and will be the focus of future work.