The invention relates to a high-temperature resistant efficient mud shale inhibitor for drilling fluid and a preparation method therefor. The high-temperature resistant efficient mud shale inhibitor is mainly used for solving the problem of the existing inhibitors that the temperature resistance and stability are poor in the aspect of inhibiting of mud shale hydration. The inhibitor contains the following ingredients in percentage by weight: 1-2% of monomer A, 1-1.5% of monomer B and 0.15% of initiator. The preparation method for the high-temperature resistant efficient mud shale inhibitor for the drilling fluid comprises the following steps: (1) proportionally adding an aqueous solution and the monomer A into a three-mouthed flask; (2) heating the mixture to the temperature of 60 DEG C, and then, dropwise adding the initiator and the monomer B into the heated mixture; and (3) after the monomer B is added completely, heating the monomer B added mixture to the temperature of 70 DEG C, carrying out reflux reaction for certain time, and cooling the reflux reaction product to room temperature, thereby obtaining the high-temperature resistant mud shale inhibitor. The high-temperature resistant efficient mud shale inhibitor for the drilling fluid can be used for improving the mud shale inhibiting action of water-base drilling fluid, lowering underground complexity and improving temperature resistance and borehole wall stability.