Abstract: Timekeeping atomic clocks mainly include hydrogen masers and cesium atomic clocks. In order to further explore the time-scale performance of different types of timekeeping atomic clocks, in this paper a study on the hydrogen maser and the hydrogen-cesium combined time scale is carried out. Firstly, the hydrogen maser is classified according to the d bulletin issued by BIPM. According to the classification results, the atomic time-scale theory is used to calculate the hydrogen maser time scale, and the analysis results are given. Then the time scales of cesium clocks are calculated and two different time scales of hydrogen-cesium combined ensembles are analyzed and explored. The results show that the time-scale fluctuation range of the hydrogen maser ensemble based on the small frequency drift is smaller, and the stability is better than the time scale of the hydrogen maser ensemble based on the larger frequency drift. The time scale stability of the hydrogen-cesium combination is better than the total cesium clock, and the results of different hydrogen-cesium combination time scale clocks are similar.