The invention relates to the technical field of lubricating equipment and discloses an automatic-oiling machine tool lubricating device which comprises a machine tool body. An oil outgoing tank is fixedly connected at the top inside the machine tool body, an oil incoming pipe is fixedly connected in the middle of the top of the oil outgoing tank, an oiling tank is fixedly connected at the top of the oil incoming pipe, a funnel is fixedly connected on the side face of the top of the oiling tank, a floating rod is movably connected inside the oil incoming pipe, and a floating ball is fixedly connected at the bottom of the floating rod and positioned inside the oil outgoing tank. Convenience is brought to oiling the oiling tank through the funnel, and convenience is brought to oiling the oil outgoing tank through the oiling tank; when the oil outgoing tank is filled with oil, the floating ball is driven to block the oil incoming pipe to enable the same to stop oiling; when oil quantity in the oil outgoing tank decreases, the floating ball is separated from the oil incoming pipe, so that convenience is brought to guiding lubricating oil in the oiling tank into the oil outgoing tank from the oil incoming pipe. The automatic-oiling machine tool lubricating device has the advantage of automatic control on adding of lubricating oil according to the oil quantity in the oil outgoing tank without manual adding of the lubricating oil.