Cloud-to-ground lightning data from the World Wide Lightning Location Network (WWLLN) along with TC track and intensity data from China Meteorological Administration (CMA) are used to study lightning activities in tropical cyclones over the Northwest Pacific from 2005 to 2009,and to investigate the relationship between inner core lightning and TC intensity changes.A definition of intensity change category of storms: rapidly intensification (RI),average intensity change (AIC) and rapidly weakening (RW) is used to analyze lighting in different intensify change cases.