A lamp hinge includes a first connector and a second connector pivotally connecting with the first connector. The first connector defines a circular groove therein. The second connector has a pivotal portion pivotally engaging the first connector, and a mounting portion connecting with a lamp head of the lamp. The pivotal portion defines a curved groove therein. The mounting portion defines a central hole therein. A plurality of ball bearings are movably sandwiched between the pivotal portion and the first connector and received in the circular groove and the curved groove. The ball bearings separate the first connector from the second connector a space. Two neighboring ball bearings define a gap therebetween, for providing passage of the electric wires of the lamp therethrough. The gap communicates with the central hole of the mounting portion of the second connector.