The invention relates to a preparation method for an omeprazole enteric coated tablet. The components comprise in percents by weight: 10-50% of omeprazole, 1.25-6.25% of superfine silica powder, 30-78% of lactose, 2-3% of copolyvinylpyrrolidone, 5-12% of crospovidone, 1.5-2.0% of sodium octadecyl fumarate and 0.5-1.0% of magnesium stearate. The preparation method comprises: uniformly mixing micronized omeprazole and superfine silica powder, sieving; sieving copolyvinylpyrrolidone, crospovidone, lactose and sodium octadecyl fumarate, uniformly mixing with omeprazole and superfine silica powder, adding into a drying-method granulator, granulating for 3-4 times, screening out integrated particles with a 60 mesh sieve and obtaining dry particles; blending uniformly the dry particles and magnesium stearate by a three-dimensional mixer, adding into a tablet press for pressing tablets; and then coating to obtain the omeprazole enteric coated tablet. The formula is simple; the preparation method helps to solve the industrialized production problem of omeprazole enteric coated tablet high-specification products such as a product with a specification of 40 mg/tablet; and the preparation is controllable in quality, the product is good in uniformity, and impurity content is low.