Electro-hydraulic proportional control technology is used for XDQ-1200 light full hydraulic core drill with the advantages of high automation level, high efficiency, easy operation and high reliability. The paper briefly introduces the performance characteristics of the drill, expounds the power head rotation, hydraulic control principles of feed system and overall electric principle design. Production test shows that the drilling operation is well with advanced drill functions of stable work, fast drilling speed, simple operation and high degree of automation.