Based on the NCEP/NCAR reanalysis data of monthly mean geopotential height, wind, vorticity, and vertical velocity, NOAA reconstructed sea surface temperature (SST) of the Indian Ocean, and the best track dataset from Joint Typhoon Waming Center (JTWC) at a 6-h interval from 1979 to 2018, the relationship between the Indian Ocean SST in the preceding spring and the concurrent summer and the summer typhoons over western North Pacific is investigated using synthetic analysis. The results are shown below. 1) The Indian Ocean sea surface temperature anomaly (SSTA) in the preceding summer, especially when the key region is located at the Indian Ocean north of the equator and the southwest Indian Ocean, has significant effects on typhoons over western North Pacific. In the years of abnormally high SST in spring over the Indian Ocean, in the later summer, the meridional vertical circulation between 110°E and 180 °E shows abnormal downdraft, corresponding to the circulation of low-level wind divergence and upper-level wind convergence, which stops the upward transport of low-level water vapor. In addition, due to the abnormally less water vapor in the middle troposphere and abnomally larger vertical shear of zonal wind, the summer typhoons over western North Pacific present characteristics of lower frequency and weaker intensity. A reverse situation is indicated in the abnormally cold years. 2) In the abnormally wam years of spring over the Indian Ocean, the western North Pacific subtropical high is strengthened and extends westward; while in the abnormally cold years, the western North Pacific subtropical high is weakened and goes eastward in the later summer, which is another probable reason for the changes of summer typhoons over western North Pacific.