Disclosed are an EGFR inhibitor free base or acid salt polycrystalline form, a preparation method therefor, and an application thereof. The present invention specifically relates to an N-(5-((4-(1-cyclopropyl-1H-indol-3-yl)pyrimidin-2-yl)amino)-2-((2-(dimethylamino)ethyl)(methyl)amino)-4-methoxyphenyl)acrylamide free base or acid salt polycrystalline form, a preparation method therefor, and an application of the polycrystalline form in preparing a drug for treating an EGFR mutant activity-mediated disease. The present invention is used for inhibiting the activity of an L858R EGFR mutant, a T790M EGFR mutant and an exon 19 deletion activating mutant etc., may be widely applied in preventing and treating cancer, especially non-small cell lung cancer and other related diseases, and is expected to develop into a new generation of EGFR inhibitors.