Based on observational data of automatic meteorological stations, radar products from Qingdao, TIANYAN radar mosaic products, and ERA5 reanalysis data, the mesoscale characteristics and environmental conditions of the heavy precipitation process occurred in the western region of Shandong Peninsula caused by the peripheral airflow of Typhoon Bavi are analyzed. The results are shown as follows. 1) During the northward movement of Bavi over the Yellow Sea, its warm and moist peripheral air and cold air come from the north converge in the region from west of Shandong Peninsula to the southeast of Shandong Province. Thus, a northeast-southwest oriented deep shear line is formed in the middle and lower troposphere, and it is on the right side of the upper-level jet stream entrance area in the upper troposphere. The low-level convergence and high-level divergence are favorable for heavy precipitation, which is located near the shear line at 850 hPa and its rightside easterly wind region. 2) In the early stage, the precipitation echo is characterized by two pre-typhoon squall lines, whose formation, development and movement are closely related to the shear line at 850 hPa. In the later stage, γ mesoscale convergence in easterly flow to the right side of the shear line continuously triggers the formation of convective cells. The composite reflectivity factor CR, differential reflectivity factor ZDR and differential phase shift rate KDP all increase significantly in Jimo, Qingdao, resulting in the hourly rainfall intensity greater than 100 mm•h-1 in Nanquan Jimo for two consecutive hours. 3) The vertical ascending motion near the shear line is deep and the convergence of water vapor flux below 850 hPa is strong, which provide dynamic lift condition and abundant water vapor for mesoscale system. At 850 hPa, the position of θse warm tongue coincides with the shear line, and the maximum value of the warm tongue reaches 352 K, which provides energy conditions for the occurrence and development of mesoscale system. In addition, the weak cold air activity in the middle and upper troposphere plays a certain role in triggering strong convective weather. 4) The area below 850 hPa with water vapor flux convergence magnitude less than or equal to -8×10-7 g•cm-2•hPa-1•s-1 is basically consistent with the heavy precipitation region. The lower the convergence center of water vapor flux and the lower the vertical ascending motion center, the more conducive it is for occurrence of heavy precipitation.