The invention relates to a synthetic method for gefitinib. The preparation method is carried out through a novel synthetic intermediate. Before a quinazoline mother ring is synthesized, hydroxyl of 3-hydroxypropenyl of a side chain is firstly converted into tosylate and in the reaction of the last step, the tosylate is replaced by morpholine, so that the operation of repeated debugging during intermediate purification treatment of each step in the whole flow can be reduced, the use level of acid and alkali and the material loss are reduced, the purification method is simplified, and the yield is improved. Moreover, as the intermediate structure has a large toluenesulfonyl group rather than a morpholine group, the melting point of the intermediate in each step is improved, thereby benefiting the purification operation.