A base for roller skates includes a skeleton and a reinforcing shell. The skeleton is made of a first material through one-time processing and is formed with a plurality of hollow areas. The reinforcing shell includes a plurality of inlaid structures respectively embedded in the hollow areas is directly disposed on the skeleton by injection molding with a second material. The second material is different from the first material. Two roller frame mounting hole sets on the base for roller skates are directly formed by the skeleton, and a brake block mounting hole and a treading platform on the base for roller skates are formed by the reinforcing shell. The base for roller skates is not made of single metal material like prior arts, making it capable of reducing fracture due to the hard and brittle characteristics of the material used in prior art.