Silicon is a key material to electro-photonic detectors, which makes the studies of laser induced damage of silicon significantly important in laser detecting and military applications. The damage characters of silicon under high-intensity nanosecond laser pulses have been investigated in this paper. The results show that the synergy of thermal, shock and spectral radiation effects of laser plasma determines the damage characters in silicon. Due to thermal and shock effects of laser plasma, the material is melt, vaporized, ionized and pushed out in laser irradiated area. This way, pits are formed and the cool ejected effluents are distributed radially. The interference between scattered and incident laser can form a periodic structure because of the periodic distribution of thermal stress in particular area. N, O and Si characteristic spectrum in laser plasma suggests that colored film is the mixture of SiOx:SiNy from laser plasma under repetitive laser pulses.