In　a　mergers　and　acquisitions(M&A),　the　knowledge　capital　of　the　combined　companies　have　the　potential　of　synergy　and　can　be　integrated　effectively,　it　is　important　for　the　combined　companies　to　know　what　factors　affect　knowledge　capital　synergy　and　how　the　synergy　forms.　This　paper　investigates　how　knowledge　capital　as　an　important　source　of　synergy　evolutions　in　a　mergers　and　acquisitions　process.　A　preliminary　evolution　process　of　knowledge　capital　synergy　is　simulated　with　system　dynamics　(SD)　model　in　this　paper.　According　to　the　model,　we　can　draw　the　conclusion　that　macro-environment　changing,　conflict　between　M&A　companies,　knowledge　acquisition　ability　of　M&A　companies　and　similarity　of　knowledge　of　M&A　companies　are　all　have　great　effect　on　knowledge　capital　synergy.　It　can　be　used　effectively　in　evaluating　possibility　of　knowledge　capital　synergy　creation　in　M&A　and　to　accelerate　the　realization　of　merger　synergies.