A continuous heavy rain course lasted in Shandong Province from 9 to 12 August 2019 mainly brought by landing typhoon Lekima. Local rainfall of Shandong peaked at night of 10 August. Reasons why the heavy rain there became the largest at night of 10 are studied by using hourly rainfall data, conventional observation data, Temperature of Black Body (TBB) observed by China FengYun-2G (FY-2G) Meteorological satellite, as well as American National Center of Environmental Prediction (NCEP) reanalysis data. Main method of this paper is diagnostic research by using both equation of zonal horizontal motion and that of atmospheric kinetic energy. The conclusions could be drawn as follows. (1) Main influence systems of the heavy rain were westerly trough on 500 hPa, southwesterly upper level jet, southeasterly low level jet, inverted trough of typhoon Lekima on 850 hPa, as well as typhoon circulation of Lekima itself. A large scale upper level jet of southwester on 200 hPa moved southeastward to affect northwest Shandong Province in 10 August. Another large scale southeasterly low level jet on 850 hPa jumped quickly northward passing Shandong Province at 0800 BJT 10. Convective clouds of both inverted trough and typhoon Lekima circulation itself moved northward over central Shandong Province successively, causing the top rainfall of that area at night of 10 due to cumulative effect. (2) The fastest east wind increasement on 850 hPa appeared at the northeast of Zhangqiu radiosonde station around 2000 BJT 10 during the rainstorm course. Results show that the main reason why east wind augmented was advection of east wind, but geostrophic deflection force term wasn’t conducive to easterly increasement. (3) Southwester jet emerged at 200 hPa at Zhangqiu radiosonde station at 2000 BJT 10, southeaster jet maintained at 850 hPa at Qingdao radiosonde station from 0800 BJT 10 to 0800 BJT 11. The rain reached its peak at night of 10 in the middle of Shandong Province, because the region was not only at the right and rear of upper level jet, but also at the left and front of low level jet simultaneously. Both kinetic energy at Zhangqiu on 200 hPa and that at Qingdao on 850 hPa augmented fastest 12 hours before wind speeds reached their maximum value of those days. Results diagnosed through kinetic energy equation show that, the item most favorable to upper level wind speed increasement on 200 hPa near Zhangqiu station was advection of potential energy, and the item most favorable to low level wind speed increasement on 850 hPa near Qingdao station was divergence of kinetic energy vertical flux. (4) Although typhoon circulation of Lekima itself acted on Shandong from 2000 BJT 10 to 0800 BJT 13, and the dynamic role of mountains in central Shandong had always been there in the course, the rainstorm there just broke out at night of 10 August. It shows that, the coupling of upper level jet with low level jet at that time might be the major factor of raising the rainfall intensity. Its roles were strengthening ascending motion, raising the whole layer water vapor transportation and adding atmospheric static instability in the central Shandong at least.