Abstract: A total of 255 fish specimens of invasive species Clarias gariepinus were collected from the main rivers of south China, to analyze its reproductive characteristics. The results showed that females spawned from May to August, and the spawning peak occurred in June and July. The distribution of egg-diameter presented a multipeak pattern. Fat coefficient and fullness coefficient had obvious seasonal changes, and had an opposite trend with gonadosomatic index. The absolute fecundity ranged from 2850 to 605720 eggs with an average of 234232 eggs, and had a positive correlation relationship with body length, weight and age. The relative fecundity varied from 20 to 445 eggs·g^-1 with an average of 165 eggs·g^-1, and initially increased with body length, weight and age, and then became stable. Absolute fecundity and relative fecundity of C. garipinus were greater than those of other Siluridae fishes. Sex ratio of C. garipinus was 1∶1.12 in breeding season, and had no obvious difference with 1∶1. The shortest mature females (body length: 174 mm; weight: 119.5 g; gonadosomatic index: 8.50%) and males (length: 250 mm; weight: 116.2 g; gonadosomatic index: 0.45%) were 1 year old with Ⅳ period gonads. The age composition of breeding population mainly consisted of ages 1 and 2, which accounted for  42.28% (age 1) and 51.68%(age 2) of the total specimens. The results suggested that reproduction characteristics (i.e. multiple batch spawning, highly relative fecundity, small eggs, mature at early age) of C. gariepinus might be conducive to its invasion in south China. It is necessary to strengthen monitoring for the wild populations of C. gariepinus, and take further measures to prevent and control this fish species in the invaded regions.