Multifunctional additive for drilling fluid

The invention relates to the technical field of oil field drilling auxiliaries, in particular to a multifunctional auxiliary for drilling fluid and a preparation method thereof, and the multifunctional auxiliary comprises the following raw materials in parts by mass: 30-60 parts of base oil, 2-10 parts of a suspending agent, 10-20 parts of an active agent, 30-50 parts of asphalt, 5-20 parts of an acidifying agent and 5-20 parts of a neutralizing agent. The multifunctional additive for the drilling fluid provided by the invention overcomes the defect of single effect of the additive for the drilling fluid in China at present, has the effects of resisting high temperature, inhibiting collapse, blocking, lubricating, reducing filtration loss and the like, and can reduce or avoid the use of additives which are less in use amount of lubricants, inhibitors and the like in the drilling fluid and easily have side effects; meanwhile, the anti-sloughing plugging performance and the filtrate loss reduction performance o