A method for making a mushroom-type hook strap for mechanical fasteners is disclosed. In a first stage of the method, a hook strap on which a plurality of hook preforms each having a substantially V-shaped free end are integrally molded. Then, in a second stage of the method, the V-shaped free end of each the hook preform is deformed into a polygonal head portion by two calendar rolls so as to form a mushroom-type hook strap that has a higher engaging percentage with the loop strap, has a longer lifetime, and is capable of providing a reliable and all-directional uniform fastening function.