The invention relates to the field of daily life, in particular to an accessory for size-adjustable slippers. The accessory comprises a shoe body mounting region and an extended shoe block, wherein both the shoe body mounting region and the extended shoe block are provided with projecting nipple bodies and concave holes; the projecting nipple bodies and the concave holes have the same outer diameter; the extended shoe block is detachable; at least one side of the extended shoe block is provided with the convex projecting nipple bodies; at least two sides are provided with the concave holes. The extended shoe block of the invention can be recombined and mounted on a shoe body mounting region and is integrated with the shoe body mounting region to avoid the risk of being stepped on the heel, thereby increasing a guarantee for consumers. The accessory is simple in principle, easy to operate, economical and practical.