he controlled directional drilling by PDM motor is the most advanced technique used insolid mineral exploration.Two types of slimhole PDM motor were developed:54mm YL-54and W65mm YL-65;two types of MWD tool using 34mm accelerator designed:ZS-1 andYS-1;two types of single shot orientator:18mm DX-18 and 38mm DG - 38; a few kindsof surface set and impregnated diamond kick-off bit;TMS cable -thru water swivel and otheraccessories. Controlled directional drilling processes are developed for deflection in various formations and in all directions.The technique has been used in more than 50 mines in China in the past decade. Some 300various directional holes have been drilled with total meterage up to 135, 000m. Typical fieldcases include: a big dog - legged hole with horrizontal displacement of 206m in a Qinghai Lead Zinc minel cluster holes drilled for exploration of deep copper ore with flat structural form inTongling, Anhui, where six side -tracked holes With different azimuth and an average depth of832m are drilled from one pilot holed hole de.iatio'n correction in an Anhui gold mine; featherholes drilled for exploration of a gold mine with steep structural form in Jinn I directional side tracked holes drilled for exploration of the Silve-Lead-Zinc ore under the lake bottom inSuzhou City, Jiangsu 3 cluster directional grout-injection holes drilled in a Tangshan coal mine,Hebei etc.The successful application of the.technique saves a great amount of drilling meterage andcost;speed-up explorationl and obtains obvious benefits.