A safety helmet liner 1 includes primarily a base fabric 2, two hot melt yarns 3, and two flexible pressing strips 4. Outer folded sections 22 corresponding to two edges  of the base fabric 2 are expanded outward, which expands an inner folded section 21 of the base fabric 2 simultaneously. After the outward folded sections 22 are expanded outward, the expanded shape of the outer folded sections 22 can be maintained by the flexible pressing strips 4 provided on the outer folded sections 22, so that the safety helmet liner 1 can be worn on a user’s head stably, thereby achieving hygiene to the user’s head.