Automated warehouse is one kind of modern warehouse with automatic storage/retrieval system(AS/RS) and a product of highly integration of modern logistics technology, warehousing technology, automation technology and computer technology. The working characteristics of each storage/retrieval machine serving multi-aisles are analyzed in automated storage and retrieval system. A mathematic model on path planning problem is constructed, a kind of new fast and improved ant colony algorithm for the order picking problem is presented. Three improvements are adopted: awaiting nodes set, selection operator and dynamic change on algorithm parameters. The performance of ant colony algorithm is greatly improved. Computer simulations show that the improved algorithm has the ability of better overall search and quickly astringency, satisfying the demands of medium or large scale work. The approach is an effective solution to order picking problem.