Abstract: In view of that the wet autogenous mills presently in use in the world are of two different lengfh-diame-ter ratio, this paper comprehensively analyzes the influence of various factors caused by the different ratio on mill effectiveness. Influence of length-diameter ratio on mill cost and liner wearing etc. are also discussed and explained, Accordingly, a tendencious opinion is proposed, taking autogenous mill of "medium-short barrel" with a length-diameter ratio of 0. 5～1. 0 as suitable. As a primary suggestion, a table of types of wet autogenous mill equipment is presented for domestic use.