The invention discloses silicon amino drilling fluid and a preparation method thereof and belongs to the technical field of resource exploration and oil exploitation. The drilling fluid is prepared from, by mass, 3-5% of sodium bentonite, 02-0.3% of tackifier, 0.3-0.5% of a coating agent, 0.5-2% of a fluid loss additive, 3-5% of a blocking agent, 0.5-1% of amidocyanogen silanol inhibitor and 0.1-0.5% of NaOH. The structural general formula of the amidocyanogen silanol inhibitor is shown in the description, wherein in the formula 8, R1 is hydrogen, hydroxyl groups, hydroxybenzoate groups, alkyl groups with 1-5 carbon or alkoxy groups with 1-5 carbon, m is any integer from 0 to 2, R2 is shown in the description, and n is any integer from 0 to 3. The drilling fluid has high inhibition performance on shale, can effectively inhibit mud making of clay, has the excellent rheological property, is little in filter loss, effectively protects reservoir easily and can meet requirements of drilling operation.