A pulsating vapor chamber has an inner board, a first outer board, a second outer board, an asymmetric loop, and a working fluid. The inner board has a first surface and a second surface. The first and second outer boards are mounted on the first surface and the second surface of the inner board respectively. The asymmetric loop is located between the first and second outer boards and has multiple channels communicating with each other in sequence. A part of the channels are formed between the first outer board and the inner board, and the remaining channels are formed between the second outer board and the inner board. With the asymmetric loop, even if the vapor chamber is disposed horizontally, pressure may be changed by different amount in the channels so that the working fluid is still able to oscillate or circulate.