The invention discloses a cross-scale broad-spectrum particle size plugging formula granularity analysis method, and relates to the field of plugging formula granularity analysis of well completion engineering in well drilling. The method disclosed by the invention comprises the following steps: performing size classification on plugging materials in a plugging formula, obtaining the granularity distribution of granular plugging materials by using a laser granularity analysis method and an imaging granularity analysis method according to the size difference, and performing weighted summation according to the granularity intervals and adding amounts of the granular plugging materials to obtain the granularity distribution of the plugging formula. By adoption of the cross-scale broad-spectrum particle size plugging formula granularity analysis method disclosed by the invention, the problem that the granularity distribution of the plugging formula across multiple scale ranges cannot be effectively obtained is solved, granularity analysis can be performed on the broad-spectrum particle size plugging formulas spanning the micrometer, millimeter, centimeter and above scales, thereby effectively evaluating the crack plugging capability of the plugging formula and providing a reference for researchers to optimize the plugging formula.