The invention provides a plugging material, the plugging material comprises nano silica and sepiolite; and the weight ratio of nano silica to sepiolite is 4-5:1-2. The invention also provides an oil base drilling fluid additive containing the plugging material, the oil base drilling fluid additive comprises 1-3 by mass parts of the plugging material, 0.5-2 by mass parts of an emulsifier, 0.5-2 by mass parts of a wetting agent and 0.1-1 by mass part of a calcium chloride aqueous solution. The invention also provides a use method of the oil base drilling fluid additive for improving the plugging performance of a drilling fluid, and the method is as follows: the oil base drilling fluid additive is proportionally added with the plugging material, the emulsifier, the wetting agent and the calcium chloride aqueous solution, and stirring and emulsifying are performed, so that the plugging property of the drilling fluid is improved.