Abstract: A method of crowdsourcing annotation for medical image data based on image comparison, includes developing an annotation task; acquiring and verifying medical images according to requirements of the annotation task, and performing statistics on the medical images that meet verification standards to obtain an amount of image data acquired; archiving the medical images that meet the verification standards to form a medical image database; setting up annotation rules, and generating annotation schemes and annotation samples according to the requirements of the annotation task and annotation rules; distributing the medical images in the medical image database to multiple crowdsourcing annotation sides, so that each medical image being annotated by the multiple crowdsourcing annotation sides; annotating, by the crowdsourcing annotation sides, the distributed medical images according to the annotation schemes and the annotation examples to form the annotated images; and merging multiple annotated images correspondi