Abstract: Based on the observation data from 59 meteorological stations in Liaoning province from 1978 to 2007, the temporal and spatial distribution characteristics of thunderstorm days were analyzed. The results indicate that average value of annual thunderstorm days is 28.1 d in Liaoning province. The number of thunderstorm days decreases with 1.2 d/ 10a during recent 30 years from the eastern and western mountain areas to middle hills, plains and coastal areas, and there are obvious seasonal and monthly changes. Thunderstorm days often occur in summer, followed in autumn, yet no in winter. Thunderstorm days increase rapidly from March to May and are stable from June to August, and then decrease speedily from September to December. The highest frequency of thunderstorm is usually from 14:00 to 20:00, followed from 20:00 to 02:00, and the lowest from 02:00 to 08:00. Average duration of annual thunderstorm days is about 175.8 d, and the longest and the shortest are 295 d and 102 d, respectively. The first day of thunderstorm days often appears in April, followed in May and March. The last day of thunderstorm days usually occurs in October, followed in September and December. In generally, the first day of thunderstorm days is ahead and the last day is delayed during recent 30 years.