With multiple nozzles and high head Pelton turbines, the increasing of nozzles will lead to mutual interference of flows in the runner, which reduces the efficiency of Pelton turbine. The working pressure at the root of bucket will increase obviously, and the safety factor of the hydropower station will be reduced. UG software was used to establish the model of runner bucket. By using CFD technique, the internal flow of a Pelton turbine with six nozzles was numerically simulated. ANSYS software was used to analyze the stress on the bucket. The runner bucket and profile line at the root were optimized. The problem of mutual interference among jets and internal flows was solved after the increasing of nozzles. The intensity and hydraulic performance of Pelton turbines were guaranteed. The designed unit has the characteristics of stable operation and high efficiency.