Abstract: This paper summarizes 20 years developments at home and abroad on the given subject.Througj analyzing 150 cases of field test results and 2 cases of long-term in-situ observations,somegeneral relationships between the base resistance/pile capacity ratio （Q_b/Q）of rock-socketed pilesunder vertical load and their length/diamter ratio（L/d）are found.They are quite in contrast with theconventional concept that rock-socketed piles are all end-bearing in nature. Mechanism that governs thementioned relationships is explained and the necessary conditions and appropriate socket lengths forrock-socketed piles of different L/d ratios to be end-bearing or frictional end-bearing are discussed.Piles not satisfyng the conditions are unnecessary to be socketed into any rock superior to moderatelyweathered stage. Finally,a general formula with empirical paranleters for reasonably determining thevertical bearing capacitu of rock-socketed piles is presented.