A simplified socket structure of miniature light bulb sets primarily comprises a shell element and a holding element that is provided with a pair of opposite resilient arms to secure a miniature light bulb in position. When the holding element along with a miniature light bulb seated therein is inserted into the shell element, the resilient arms are urged by the walls of the shell element to move toward each other to firmly grasp the light bulb. Thus the miniature light bulb socket according to the invention has the advantages of simplified structures and promoted gripping effect.