Abstract: Based on that whether there is a positive IOD event in the same year, the El Nio Modoki events are divided into two kinds: p-ENM and ENM-IOD. Two typical p-ENM events (2004;2009) and two typical ENM-IOD events (1991;1994) are selected. The results of comparative analysis show that the same events have similar tropical cyclone genesis patterns while tropical cyclone genesis of the Northwest Pacific in ENM-IOD autumn shifts eastward compared with that in p-ENM autumn. The two p-ENM events have weak and narrow westerly wind anomaly area which is observed in the west of 165E, however the two ENM-IOD events have much stronger equatorial westerly wind anomaly that extends across the dateline. So the ENM-IOD autumn monsoon trough prolongs about 20 farther east than the p-ENM monsoon trough. At the same time, autumn vertical wind shear in the Northwest Pacific is weaker and narrower in p-ENM than in ENM-IOD. The differences in position of monsoon trough and vertical wind shear distribution make the tropical cyclone genesis location farther east in ENM-IOD autumn than in p-ENM autumn.