An automatic mixing and charging device of mining explosive and oil comprises an oil spraying system, an explosive and oil mixing pipe and a charging device. The oil spraying system is composed of an oil tank, a pressure gage, a pressure air gate valve for adjusting air pressure and an oil conveying pipe. One end of the explosive and oil mixing pipe is connected with the charging device, the other end of the explosive and oil mixing pipe is connected with an explosive conveying hose communicated with a blast hole, and a connector connected with the oil conveying pipe is formed in the middle of the explosive and oil mixing pipe. After the air pressure is connected, diesel oil in the oil tank and explosive sprayed out of the charging device are fully mixed in the explosive and oil mixing pipe through the oil conveying pipe, and then the diesel and the explosive are pressed in the blast hole through the explosive conveying hose. According to the automatic mixing and charging device, scaling automatic even mixing of the explosive and oil and automatic charging can be achieved, the charging powder return rate can be reduced, charging quality can be improved, charging efficiency is improved, and the detonation cost is saved.