Abstract When the ionosphere is strongly disturbed, the performances of satellite navigation and positioning systems as well as various radio communication systems are reduced due to the electronic density gradient and ionospheric irregularities. However, the characteristics and coupling mechanism of ionospheric disturbances caused by meteorological activities in the lower atmosphere are still unclear. Therefore, as one of the most severe surface weather changes, it is of great practical significance to study the influence of typhoons on the ionosphere. In this paper, the ionospheric irregularities during 20 typhoons landing in Taiwan, Guangdong Province and the Philippines during the quiet solar and geomagnetic activities from 2006 to 2018 were analyzed by using the rate of change in the total electron content (ROTI). Through a statistical analysis of 20 typhoons, it was found that there are ionospheric irregularities during 15 typhoons. There was a certain correlation between ionospheric disturbances and the typhoons. Both typhoons MANGKHUT and HAIMA landed in Guangdong Province, but ROTI > 0.5 $TEC·{min}^{-1}$ was detected only when typhoon HAIMA made landfall in Guangdong. This phenomenon can be explained by the influence of terrain on the acoustic gravity waves. The HAIMA typhoon passed through Lianhua Mountain (altitude: 1336 m). When the typhoon landed in higher terrain, due to the resistance effect of the high terrain, the high rate of decline in the air creates an ideal condition for the development of the acoustic gravity waves. During the impact of the typhoon, the acoustic gravity waves can spread to the ionosphere height and have an impact on the ionosphere.