The invention discloses a pipeline leakage automatic monitoring and alarm device. The structure of the pipeline leakage automatic monitoring and alarm device comprises a valve body, an oil incoming pipe, an inlet connection flange, an upper flange seat, a bolt, a pressure transmission device, a pressure sensor, a cable, an outlet connection flange, an oil outgoing pipe, a channel, a connecting opening, a rubber sealing ring, a sealing filler and a conical valve core; and one end of the oil incoming pipe is installed at the middle of the left end of the valve body by means of welding. Accordingto the structure of the pipeline leakage automatic monitoring and alarm device of the invention, the pressure transmission device is installed at the upper end of the valve body; a valve rod inside the pressure transmission device is matched with an oil passage; when oil leakage occurs at the joint of two oil pipes, the pressure intensity of oil flowing through the channel decreases, and the pressure transmission device detects the oil pressure change and transmits pressure signals to the pressure sensor; and an alarm connected with the sensor will give out an alarm, so as to prompt notify maintenance personnel to perform maintenance, and therefore, the normal operation of the oil pipes can be ensured.