Abstract: Based on the data from in-situ rock-socketed test piles, the vertical bearing mechanism of rock-socketed piles is deeply discussed in this paper. Further, the idea to determine the vertical bearing capacity of rock-socketed piles by the settlement of pile top is suggested with the corresponding calculating method presented. And the method can consider the development of side friction of soil along the pile shaft and the end bearing by rock at the bottom, which is especially suitable for the determination of vertical bearing capacity of ultra-long, cast-in-place and rock-socketed piles. Finally, an analysis is made on the static loading test data of a rock-socketed pile in a bridge, the results of which show a good agreement with those measured.