Effects of cloud condensation nuclei (CCN) concentration on explicit-deep convection simulations of precipitation associated with a squall line that developed in Guangdong Province, China are investigated using the Weather Research and Forecasting model. Four groups of simulations are conducted, each with a different bulk microphysical scheme (Morrison, Thompson09, Thompson07, and WDM6) and consisting of three members with low, median, and high CCN concentration, respectively. Changes caused by the CCN concentration variation in the surface rainfall rates within the regions of deep convection, stratiform cloud, and shallow convection, as well as in their areas, are compared among the four groups of simulations. Then the microphysical processes and strength of dynamical circulation in the simulations are examined. It is found that: (1) The CCN－precipitation impacts among the four groups of simulations exhibit both similarities and differences, due to the direct or indirect relationships between the microphysical processes and CCN concentration, the complicated linkage among various microphysical processes, and the nonlinear coupling between microphysical and dynamical processes.(2) The simulated CCN－precipitation impacts are the most significant with the Thompson09 or Thompson07 scheme and the least notable with the WDM6 scheme.(3) In these experiments, precipitation is delayed and weakened during the early stage of the simulations and rainfall amount is also decreased during the late stage, while the CCN－precipitation impacts are more complicated during the mature stage of the simulated squall line.