For　routing　industrial　circuits,　the　Steiner　minimal　tree　(SMT)　model　can　be　applied　in　different　routing　problems,　such　as　wirelength　optimization,　congestion　reduction,　and　delay　optimization.　In　this　paper,　an　efficient　VLSI　routing　algorithm　employing　novel　discrete　particle　swarm　optimization　(PSO)　and　multi-stage　transformation　is　proposed　to　build　two　types　of　SMT,　including　X-architecture　Steiner　minimal　tree　and　rectilinear　Steiner　minimal　tree.　Firstly,　to　simultaneously　handle　two　types　of　SMT　problems,　an　effective　encoding　strategy　is　proposed　to　be　more　suitable　for　PSO　and　thus　it　can　overcome　the　difficulty　of　designing　different　algorithms　for　different　routing　architectures.　Secondly,　a　multi-stage　transformation　strategy　is　presented　to　expand　the　search　space　of　the　proposed　algorithm　and　accelerate　the　convergence　speed　of　the　proposed　algorithm.　Various　combinations　of　multi-stage　transformation　strategies　have　been　tested　to　highlight　the　best　combination.　Furthermore,　the　various　genetic　operators　combined　with　union-find　data　structure　strategy　are　proposed　to　construct　the　novel　and　effective　discrete　particle　update　formula.　Experimental　simulation　results　on　industrial　circuits　show　that　the　proposed　algorithm　can　get　the　best　solutions　among　the　existing　algorithms.