Through a low temperature (500 °C) catalyst-free chemical vapor deposition (CVD) method, ZnS nanowires with lengths of up to tens of micrometers were grown in situ on a substrate with CS2, used as the sulfur source, for the first time. The nanowires were characterized and a new crystallographic orientation relationship between wurtzite and sphalerite ZnS phases is identified in the ZnS nanowires: the individual ZnS nanowires consist of both wurtzite and sphalerite structures coexisting as two parallel components along the axis direction.