A lamp socket includes a double open end, conical socket shell, a socket cap covered on one open end of the conical socket shell and having a plurality of through holes, a metal contact ring fastened to two mounting tabs inside the conical socket shell for receiving the ring contact of a bulb, and a metal contact plate fastened to a transverse frame within the bottom open end of the conical socket shell for the contact of the tip contact of the bulb being threaded into the metal socket ring, the conical socket shell and the metal contact ring defining a water passage therebetween in communication with the through holes on the socket cap for guiding rain water out of the lamp socket.