A swimming goggle includes an eyepiece frame, a head strap and two fastening assemblies for connecting the eyepiece frame and the head strap. Both sides of the eyepiece frame have a through-hole respectively. Both ends of the head strap have protrusions. The fastening assembly includes a fastening base and a shroud assembled with the fastening base. The fastening base has an operating arm formed with an engaging piece. The fastening base has three tongues, a locking hole corresponding to the through-hole, and a trough for allowing the head strap to pass through. The shroud has a hook disposed through the through-hole and engaged with the locking hole. The inner edge of the shroud is provided with three notches for allowing the three tongues to be inserted therein. By this structure, the present invention can be assembled firmly, and the head strap can be tightened or loosened easily.
