CMC-LV can be used in oil drilling as the mud stabilizer and water-holding agent to protect the oil well. The product has the advantages of high mud yield and low fluid loss, The drilling mud with CMC-LV enables the shaft lining to form thin and solid and low-permeability filter cakes and then to reduce fluid loss. 2. Adding CMC-LV to the drilling mud enables the drilling machine to obtain low initial gel strength, the mud to discharge air in it easily and debris to be discarded in a mud pit quickly. 3. Like other suspended dispersions, the drilling mud has a certain life period that can be prolonged when CMC-LV is added to stabilize it. 4. The drilling mud with CMC-LV is seldom affected by mycete, so there is no need to maintain high pH value or use preservatives. 5. The drilling mud with CMC-LV can be used as the treating agent of flushing fluid to prevent pollution of various kinds of soluble salts. 6. The drilling mud with CMC-LV has favorable stability and can still reduce fluid loss even at the temperature above 150℃.