The invention discloses a quick QFN chip plastic package image obtaining and amplifying method. The method comprises the following steps of (1) preprocessing a plurality of QFN plastic package images acquired by a visual detection system; (2) performing connected region marking and judgment on preprocessing results of the plastic package images, and extracting a single QFN plastic package image from a connected region meeting a condition; (3) preprocessing the extracted single plastic package image; (4) performing rotary correction on a preprocessing result of the single plastic package image; (5) performing quick image amplification on a rotary correction result of the single plastic package image; (6) if a non-extracted connected region meeting the condition also exists currently, entering the step (2), otherwise, ending the processing of the current QFN plastic package images, and entering the processing of next QFN plastic package images. The method provides a technical basis for high-precision online detection of surface defects of a QFN chip.