In order to improve the huge volume and avoid expensive cost of the existing large diameter deep hole drilling machine, a new type of large-diameter spindle rig is practically developed, which has compact structure with advantages of effective drilling, flexible operation and moderate price and is more adaptable to Chinese market. This paper focuses on the unique design of transfer case and hoisting device; on the basis of spindle type rig, the innovation was carried out on the design of transmission route and structure components to give the rig ability to adapt to low speed and heavy loading in large diameter deep hole drilling.