Harmful algal blooms (HABs) in coastal waters have made a great negative impact on marine environment and ecosystem, aquaculture industry and human health worldwide. There are a number of strategies that can mitigate HABs, including physical and chemical means, but none of these methods has been totally successful due to the high cost and potential hazard to the aquatic ecosystems. Therefore, it is urgent and beneficial to develop a more economical and environment-friendly algicidal agents to control HABs. It has been reported that certain marine bacteria play an important role in inhibiting the growth of red tide phytoplankton. Many bacterial strains isolated from HABs affected waters have algicidal effects on several HABs species. Thus, the algicidal bacteria could potentially be of great use in HABs controlling. In this paper, a marine algicidal bacterial strain N10 against Prorocentrum micans was isolated from a HABs area in Mirs Bay in south China. The algicidal activity and algicidal mode of strain N10 were tested using 48-well microplate liquid infection methods. Results showed that P. micans which exposed to strain N10 lost its moveability, then inflated and cellular components aggregated, and finally lysed. The algicidal activity was in a concentration-dependent manner. The test of bacterial cultures added to algal cultures at volume ratio of 1: 10 showed the strongest algicidal activity, 83% P. micans lysed within 24 h, and all lysed at 72 h, simultaneously, bacterial density decreased slowly from 7.6×10⁸ CFU/mL to 5.3×10⁸ CFU/mL in 72 h, then decreased sharply to 2.5×10⁶ CFU/mL at 120 h. In the test of 1: 20, 71% P. micans lysed within 24 h, and 77% lysed at the end of 120 h, companied by the bacterial density increasing from 4.0×10⁸ CFU/mL to 5.8×10⁸ CFU/mL within 24 h, then decreasing sharply to 9.0×10⁵ CFU/mL at 120 h. In the test of 1: 100, 39% P. micans lysed within 24 h, then alga cells kept increasing, and only showed a significant inhibiting effect on the growth of alga comparing to that of control test, while the bacterial density decreased sharply from 8.3×10⁷ CFU/mL to 8.8×10⁵ CFU/mL within 48 h, and maintaining at this low density level to the end with 1.2×10⁶ CFU/mL. The density of P. micans exposed to bacterial cultures decreased from (1.75±0.3)×10⁴ cells/mL to (0.53±0.1)×10⁴ cells/mL within 48 h, while that of bacterial culture filtrates, heated bacterial filtrates and control test increased to (4.7±0.2)×10⁴ cells/mL, (5.0±0.6)×10⁴ cells/mL and (5.0±0.3)×10⁴ cells/mL, respectively. It indicated that P. micans lysed by strain N10 in a direct manner. Sequence analysis based on 16S rRNA and performed by BLAST, combined with morphological and physiological biochemical characteristics of bacterium showed the strain N10 belonged to genus of Muricauda sp. in Flavobacteriaceae.