A penetrating illuminator for vein observation, including a case, a lens and a light hole in the upper case, a circuit board in the case, a power source and an LED lamp. The case includes an upper part and a lower part; the rims of the upper case and lower case are in the shape of a circular arc while the top of the upper case is made into the shape of an arc protruding from the center. The lower case is rear-connected to a handle at an obtuse angle. Configured as a child's hand, it is especially suitable for use on children. Simply place the hand, with palm down, over the illuminator emitting penetrating light. A fixing stand is provided, including a base plate and a rod in the center of the base plate, wherein a groove is provided to accept the handle.