His short article from 1973 in which he lays out the principles of deep ecology as contrasted with shallow ecology is online here: The Shallow and the Deep, Long-Range Ecology Movement (and probably elsewhere). Some excerpts:
I. The Shallow Ecology movement:
Fight against pollution and resource depletion.
Central objective: the health and affluence of people in the developed countries.
II. The Deep Ecology movement:
1. Rejection of the man-in-environment image in favor the relational, total-field image. [...]
2. Biospherical egalitarianism-in principle. [...]
3. Principles of diversity and of symbiosis. [...]
4. Anti-class posture. [...]
5. Fight against pollution and resource depletion. [...]
6. Complexity, not complication. [...]
7. Local autonomy and decentralization. [...]
See also the Foundation for Deep Ecology, which has a good summary of the movement's history.