The invention relates to strong-inhibition high-blocking-performance double-protection drilling fluid, a preparation method thereof and a drilling composition. The drilling fluid is mainly composed of, by weight, 2-3 parts of bentonite, 0.3-0.5 part of polyacrylamide potassium salt, 0.2-0.4 part of polyanionic cellulose, 2-3 parts of pre-gelatinized starch, 2-3 parts of emulsified paraffin, 2-3 parts of blocking agent, 0.04-0.06 part of xanthan gum, 0.1-0.3 part of pH regulator, 0-2 parts of weighting agent and 1-2 parts of rock debris. The drilling fluid is mainly compounded by water, the polyacrylamide potassium salt, polyanionic cellulose, the pre-gelatinized starch, emulsified paraffin, the blocking agent, the xanthan gum and the rock debris; the raw materials present good inhibiting performance and blocking performance on fractured mudstone strata at low using amount, so that the drilling fluid can effectively avoid accidents like well leakage and well collapse, and safety and success rate of drilling construction are improved.