This paper introduces the stress-dispersion and self-locking type pre-stressed anchor rod technology used in danjiangkou dam heightening project. The special reaming tools and self-locking type anchor with reliable performance and reasonable structure were developed to complete the difficult 50m high precision drilling in the project. With this anchorage technology, stress concentration in the inner anchorage section was improved; ordinary anchor pre-stress transmission to base through bonding between inner anchorage body and hole wall was changed by the use of self-locking inner anchors designed for the hole enlarged sections with dispersed pressure directly applying on the base at different depth. In this case, the anchoring force will not lose along with bond force decreasing, long-term anchoring can be ensured.