The spatial and temporal distribution of lightning activity and its relationship with tropical cyclone (TC) intensity change for 228 TCs over the Northwest Pacific are studied using 10 years (2005-2014) of time series data provided by the WWLLN (World-Wide Lightning Location Network) along with TC position and intensity data from China Meteorological Administration. The average flash rate shows an oscillatory variation from 2005 to 2014, and TC flash rate in the summer half year is higher than that in the winter half year. The average flash rate increases in the morning and decreases obviously in the night with the maximum at 1200 LT (local time) and the minimum at 0600 LT. TCs exhibit three distinct regions of electrical activity, with higher flash density in both the inner core and outer rainband and the minimum in the inner rainband. The azimuthal distribution of flash density is asymmetric, and the highest flash density appears to the south of the TC center. Lightning activity at six TC intensity levels in the inner core is different from that in the outer rainband when the TC intensity changes. Lightning activity in the inner core is more active than in the outer rainband, and the highest flash density appears in rapid intensification (RI) cases and average intensity change (AIC) cases for the inner core and outer rainband, respectively. Lightning for RI cases often occurs in medium intensity TCs, while rapid weakening (RW) cases are at strong TCs. For RI cases, flash density changes with time are more evident in the inner core than in the outer rainband and the whole TC region, which indicates that lightning activity in the inner core could be a better indicator for short-term RI forecast.