Because of the characteristics of safety, environmental protection, economy and high efficiency, the mine curtain grouting has been successfully implemented in mines with good effects of water plugging. While in strong karst area, the water plugging effect will be directly influenced by the dynamic water grouting technique, especially by the plugging quality of main water channel, which is the key factor affecting the success of the project. With the background of a curtain grouting engineering in Fankou lead-zinc mine of Guangzhou, the paper discusses the grouting plugging technology for main water channel in strong karst area.