The central Qinghai-Xizang Plateau is located in the transition zone between the mid-latitude wester‐ lies and the Asian monsoon，with complex circulation systems and water vapor sources. In the studies of lake-at‐mosphere interaction in the Qinghai-Xizang Plateau，little attention has been paid to the dependence of lake effect on background circulation to understand the mechanism of lake affecting extreme precipitation. To further understand the mechanism of lake influence on extreme precipitation，this study objectively classifies the dominant synoptic patterns responsible for the regional extreme precipitation events in autumn over the central QinghaiXizang Plateau with lakes densely distributed to analyze the characteristics and differences of lake effects under different dominant synoptic patterns. Based on the CMFD precipitation data and ERA5 reanalysis data during 1979 to 2018，1358 regional extreme precipitation events were detected in autumn over the central QinghaiXizang Plateau，and it was found that the regional extreme precipitation events contributed more than 40% of the total autumn precipitation in most parts of the central Qinghai-Xizang Plateau with the large centers of regional extreme precipitation amount mainly concentrated in the Nam co basin and the small lakes in the north，that is al‐ so the region with high occurrence probability of extreme precipitation when regional extreme precipitation event occurs. Then，the spectral clustering method was used to analyze the atmospheric circulation over the central Qinghai-Xizang Plateau during the regional extreme precipitation events and identified three dominant synoptic pat‐ terns responsible for the regional extreme precipitation events in autumn over the central Qinghai-Xizang Plateau：precipitation in the southern mountainous areas caused by weak convergence airflow（P1 type），precipitation in the northeast downstream under the control of monsoonal southwest airflow（P2 type），and precipitation near lakes under the influence of southwest airflow in front of the westerly trough（P3 type）. They lead to 48. 8%，42. 3% and 8. 8% of the total occurrences of regional extreme precipitation events in autumn，respectively. P1 and P2 types mainly occur in September，and P3 type mainly occurs in October. The physical mechanism of the regional extreme precipitation occurrences is explained by analyzing the high and low level configuration of large-scale circulation fields and their anomalies under different synoptic patterns. Furthermore，multiple sensitivity experiments were conducted to reveal the relative importance of the influence of lake clusters in the central Qinghai-Xizang Plateau on regional extreme precipitation events under different synoptic patterns，and found that the lake clusters can lead to the precipitation amount averaged over the central Qinghai-Xizang Plateau reduced by 2. 37%，increased by 12. 11% and increased by 138. 37% under the P1，P2 and P3 types，respectively. The lake effect under the P3 type is the most significant among the three synoptic types，making it a synoptic pattern prone to lake effect. Further mechanistic analysis shows that the enhancement of low-level instability and water vapor convergence over the lake and surroundings areas induced by the heating and moistening effect of lake play an important role in the formation of the regional extreme precipitation under the synoptic pattern P3. This research has identified the dominant synoptic patterns responsible for the regional extreme precipitation events over the central Qinghai-Xizang Plateau in autumn and revealed the relative importance of lake effects on regional extreme precipitation under different dominant synoptic patterns，providing necessary reference for further improving the prediction level of regional extreme precipitation.