The utility model relates to a paper collecting device of a folding machine, which effectively solves the problems that the output of subsequent folded finished products is influenced due to paper accumulation caused by untimely manual paper collection, and the quantity of the finished products is counted by mistake due to negligence. According to the technical scheme, the device comprises a box body, a plurality of standby paper collecting boxes are stacked in the box body, when the standby paper collecting boxes outside the box body collect a set number of finished products, the transverse plate is pushed through the cam to push the standby paper collecting boxes on the uppermost layer in the box body out of the box body, the paper collecting boxes collecting the finished products are pushed to the inclined plate of the sliding way, and the paper collecting boxes collecting the finished products temporarily stay in the sliding way; according to the device, paper can be automaticallycollected, the number of the paper collected in each paper collecting box is consistent, the workload of workers is reduced, and the workers can conveniently count folded finished products.