The present invention provides a zipper head assembly structure. The zipper head assembly structure includes a sliding member, an elastic member and a retaining member. The sliding member has a base portion, a first lateral wall portion, a second lateral wall portion and a seat portion. The base portion has at least one retaining block. The retaining block has an inner surface inclined at an adjustable angle relative to an inner surface of the base portion. The retaining member has a positioning portion disposed on an end thereof and a retaining body disposed on another end thereof. Therefore, the retaining portion can be restricted by the bottom side surface of the at least one retaining block and can be movably retained on a predetermined plane without being changed by a change of the adjustable angle.