A problem of worker assignment in cellular manufacturing (CM) environment is studied in this paper. The worker assignment problem is an NP-complete problem. In this paper, worker assignment method is modeled based on the principles of particle swarm optimization (PSO). PSO applies a collaborative population-based search, which models over the social behavior of fish schooling and bird flocking. PSO system combines local search method through self-experience with global search methods through neighboring experience, attempting to balance the exploration-exploitation trade-off which determines the efficiency and accuracy of an optimization. An effect of velocity controlled for the PSO's is newly included in this paper. We applied the adaptation and implementation of the PSO search strategy to the worker assignment problem. Typical application examples are also presented: the results demonstrate that the velocity information is an important factor for searching best solution and our method is a viable approach for the worker assignment problem.