Typhoon YAGI (2018) weakened from severe tropical storm to tropical depression from 13 to 14 August 2018, which caused heavy precipitation in Shandong and induced tornados. Meteorological departments have conducted particular field investigation of tornado disasters. Based on high-resolution images of 6 tornado tracks by drone aerial photography and field investigation on damaged buildings, broken trees, and lodging crops, it is concluded that the tornados reached EF2 scale in Jianglou Town, Binzhou City and Yanwo Town, Dongying City and EF0/EF1 scale in other places. These tornados occurred in the mini supercells embedded in the outer rain bands located in the right-front direction relative to the track of residual low-pressure circulation; the tornado in Binzhou was the closest to the center of residual low-pressure circulation, about 150 km, while that in Weifang was the farthest, about 400 km. The mini supercells moved within rain bands from south to north or from southeast to northwest characterized by smaller scale, lower echo top, strong reflectivity factor at the bottom of the storm, and inflow notch and hook echo at low level; radial velocity products had strong positive and negative velocity pairs. When the original adaptation parameters of the radar system are used to calculate the mesocyclone (M) and the tornado vortex signature (TVS) products, among the 6 tornados, M can be identified for one tornado, and TVS for two tornadoes; when using modified adaptation parameters, the radar system gave out 6 Ms and 4 TVSs before the occurrence of the tornados. The weak M and TVS can be identified in advance by optimizing the adaptation parameters, which is beneficial to the warning of tornado.