The　micro-leakage　internal　spherical　detector　is　a　new　type　of　pipeline　leakage　detection　method　whose　movement　in　the　pipeline　is　essential　for　its　design.　This　paper　uses　the　numerical　simulation　method　to　analyze　the　detector’s　dynamics.　The　motion　of　the　spherical　detector　in　the　horizontal　liquid　transport　pipeline　is　simulated　for　the　liquid　with　different　viscosity.　The　result　shows　that　the　detector　is　mainly　in　a　rolling　state　during　the　movement,　and　its　angular　velocity　has　periodic　fluctuations.　Through　this　simulation,　the　movement　mode　of　the　spherical　detector　is　obtained,　which　provides　help　for　the　subsequent　design　of　the　micro-leakage　internal　spherical　detector.　©　2024　SPIE.