Based on XY-8 drilling rig, modular design was adopted to develop DB30 multifunction drilling rig, which can be used not only for small diameter deep hole coring drilling but also for large diameter cemented carbide drilling and water drilling. This drilling machine is driven by frequency conversion motor with simplified transmission chain, the transmission efficiency is improved; by the advanced supporting technologies and mature electronic control technology, the rig automation degree is greatly improved. The paper briefly introduces this rig about its technical scheme, technical parameters, structure design, technical advantages and practical application.