An X-ray device which is especially applicable to the X-ray imaging for child at the age of 0-3 is provided. The X-ray device can use the X-ray tube (10) which uses the molybdenum target or rhodium target (12) to produce the soft X-ray by the tube voltage between 25 and 50 kV. The synchronous-exposing equipment contained in the X-ray device may identify the still status and the breath, pulse status suitable for exposure of the child, automatically select the optimal exposing time so that it can acquire a clear X-ray image through only one X-ray exposure, thus prevent the human body from the needless X-ray radiation caused by the multiple X-ray exposures, and also improve the service efficiency of the equipment.