A vapor chamber includes a casing (1), a working liquid, and a capillary film (2). The casing (1) includes a heat-absorbing sheet (1a) and a heat-releasing sheet (1b) opposite to the heat-absorbing sheet (1a). The casing (1) includes a sealed space (S) therein. The working liquid is filled in the sealed space (S). The capillary film (2) is received in the sealed space (S) and contacts the working liquid. The capillary film (2) is produced from sintering a mixture including thermally conductive particles of at least two different lengths.