Steiner　minimal　tree　construction　is　a　key　step　in　the　physical　design　of　Very　Large　Scale　Integration　(VLSI).　Further　considering　X-architecture　with　better　wirelength　optimization　and　allowing　wires　to　pass　through　obstacles　to　a　certain　extent　before　signal　distortion,　a　novel　X-architecture　Steiner　Minimal　Tree　with　Limited　Routing　Length　inside　Obstacle　(XSMT-LRLO)　problem　is　formed.　Therefore,　the　XSMT-LRLO　based　on　Discrete　Particle　Swarm　Optimization　algorithm　(XSMT-LRLO-DPSO)　is　proposed.　Firstly,　in　order　to　significantly　reduce　the　times　of　evaluations,　a　preprocessing　strategy　based　on　a　lookup　table　is　proposed.　Secondly,　XSMT-LRLO-DPSO　is　effectively　en-coded　by　adopting　the　edge-point　pairs　encoding　method　adapted　to　an　evolutionary　iterative　process.　Then,　aiming　at　the　XSMT-LRLO　problem,　which　is　a　discrete　problem,　a　discrete　update　strategy　based　on　mutation　operation　and　crossover　operation　is　proposed.　Finally,　adjustment　and　refinement　strategies　are　introduced　to　respectively　improve　the　obstacles　bypassing　ability　and　wirelength　optimization　ability　of　the　proposed　algorithm.　The　experimental　results　show　that　the　proposed　algorithm　makes　full　use　of　the　routing　resources　within　the　obstacles,　and　effectively　saves　routing　resources.　Compared　with　similar　algorithms,　the　proposed　algorithm　has　the　strongest　wirelength　optimization　ability.　©　2021　IEEE.