Abstract: Lost circulations were continually encountered during drilling and cementing operations of well LXC-005, and the main lost zones are coal beds in the fracture belts and sand zones with extremely low leaking pressure. Eleven times of plugging operations were conducted using drilling fluid made from composite plugging materials and cement, but without any effect. A hybrid plugging technology is adopted, i.e., use the composite plugging drilling fluid for bridging firstly, and then plug with the colloid composite cement slurry made from composite plugging drilling fluid and cement. Two times of plugging operations were conducted using the colloid composite cement slurry, and the lost circulation zones were finally sealed off. A stable hole was achieved for running casing and cementing, and without any trouble encountered during casing and cementing. It has been proved that the colloid composite cement slurry is suitable for plugging the sandstone of large pores and fractured coal bed.