On the basis of the summer precipitation data from North China, the Madden–Julian Oscillation (MJO) index, and a reanalysis of the circulation data from the National Centers for Environmental Prediction/National Center for Atmospheric Research using statistical methods, this study analyzed the relationship between the MJO and summer precipitation in North China in 2018 and its influence mechanism. Results show the following: (1) The MJO is closely related to the summer precipitation in North China. Although the MJO cannot move to a higher latitude and directly affect the summer precipitation in North China, the cyclone in the MJO convective region will trigger an anticyclonic circulation to the north. During the slow eastward movement of the cyclone–anticyclone pair, the anticyclone at a higher latitude will directly affect the summer precipitation in North China; that is, the MJO will indirectly affect the summer precipitation in North China. When the MJO is in phases 5 and 6, there will be an obvious precipitation weather process in North China in summer. However, the precipitation intensity is related to the amplitude of the MJO. (2) In terms of the influence mechanism. At 850 hPa, along with the eastward movement of the MJO’s cyclone–anticyclone pair, the south wind water vapor transport (corresponding to RMM1) or the southeast wind water vapor transport (corresponding to RMM2) in summer in North China will be enhanced, which is beneficial to the precipitation weather process. At 500 hPa, the propagation of the MJO disturbance to the mid–high latitude will induce the subtropical high to move to the vicinity of the Korean Peninsula and strengthen it so that it will act as a barrier to the westerly trough and be favorable to the ascending motion in North China. Therefore, this is beneficial to the occurrence of summer weather precipitation in North China. (3) The MJO can be used to provide extended-range forecasts for summer precipitation in North China.