In order to increase the output and specific speed of Pelton turbines, the method of increasing nozzle number is usually adopted. However, the increasing nozzle will lead to mutual interference of internal flows of the runner, which reduces the efficiency of Pelton turbines. By using CFD technique, the internal flow of Pelton turbines runner with six nozzles was numerically simulated. Through the calculation results of mutual flow between bucket number and nozzle number, we found that 21 buckets for runner in Pelton turbines with six nozzles was matching with the nozzle number. The velocity and pressure distribution and current path line of single bucket during the whole jet accepting process have been obtained. The interference of internal flow of the runner during the multi-nozzle acting at the same time has been obtained as well. All these provided references for the practical operation of hydropower station. 