A large part of Inner Mongolia has temperate mainland monsoon climate, which is fragile, complex, and diverse. As an important ecological security barrier in northern China, Inner Mongolia has experienced significant changes in summer temperature and precipitation under the background of global warming, and its sensitivity to climate change is becoming increasingly prominent. In this study, various characteristics of summer meteorological elements and their responses to El Niño events in Inner Mongolia in the past 60 years were analyzed on the basis of the historical observation of meteorological stations and global reanalysis data. The following conclusions were drawn. (1) In the past 60 years, precipitation in most parts of central and eastern Inner Mongolia decreased in summer, whereas temperature in the whole region increased. (2) The correlation between El Niño index in winter and meteorological factors in summer of the following year was characterized by interdecadal variation. In the following summer, eastern El Niño in most areas in Inner Mongolia had more precipitation and lower temperature. Central El Niño had more precipitation in the northwest of Inner Mongolia, less precipitation in most parts of the middle and east, and higher temperature in the whole region. (3) The main reasons of summer precipitation differences in various El Niño types included the different intensities and locations of the subtropical high in the Central and Western Pacific Ocean, abnormal anticyclone circulation, and circulation anomalies at middle and high latitudes in two types of El Niño events. In the following summer of eastern El Niño, the subtropical high was southward compared with that in the past, and double resistance circulation anomalies appeared at middle and high latitudes of Eurasia and Asia. The northerly airflow between the low trough cold vortex and the high upstream resistance caused the water vapor of the Arctic Ocean and the water vapor of the Pacific Ocean on the west side of the subtropical high to converge in North China and be transported to the northeast, resulting in more precipitation in Inner Mongolia. For the central type, the location of the subtropical high was west by north; consequently, water vapor moved from south to east. Anticyclone circulation anomalies at middle and high latitudes are not conducive to water vapor transport at high latitudes, thereby reducing precipitation and water vapor transport in most parts of Inner Mongolia. (4) Water vapor transport in summer monsoon was caused by the sea surface temperature anomaly in the following summer in the Indian Ocean and implicated in summer precipitation in Inner Mongolia.