The invention provides a roller electromagnetic-push-and-pull size-changed manual-assisted electric branch mulberry picker. The roller electromagnetic-push-and-pull size-changed manual-assisted electric branch mulberry picker comprises handles, a supporting rod, a spring, a picking device and a collecting bag, wherein the spring, the supporting rod and the picking device are fixedly mounted on the handles, the supporting rod is mounted on the handles and is hinged to the handles, the picking device consists of rollers, telescopic rods, springs and shear knives, the springs are compression springs, one end of each telescopic rod is connected with one corresponding roller, the other end of each telescopic rod penetrates through one corresponding spring and a through hole formed in one corresponding handle and is connected with the corresponding handle, one end of each connecting rod is fixed on one corresponding telescopic rod through a bolt, the other end of each connecting rod penetrates through an axial hole formed in one corresponding shear knife, cutting edges of the shear knives are serrate, and U-shaped grooves are formed in outer circle faces of the rollers; and the handles are manually assisted, a power switch is turned on, electromagnetic push-and-pull devices drive the shear knives to reciprocate, the rollers rotate on mulberry branches, fruit stems of mulberries are cut off by the shear knives, and the mulberries fall into the collecting bag.