To　investigate　the　influencing　mechanism　of　helping　behavior　on　evacuation　dynamics　of　heterogeneous　crowds,　a　revised　social　force　model　that　incorporates　the　helping　behavior　is　proposed　in　this　paper.　The　influence　factors　including　following　strategy,　assisted　proportion,　exit　angle,　exit　position　and　width,　initial　distribution　and　body　size　of　assisted　person,　etc.　on　evacuation　process　are　systematically　analyzed.　Simulation　results　indicate　that　the　helping　behavior　has　a　significant　impact　on　the　evacuation　process.　The　helping　relation　is　vulnerable　to　be　broken　at　the　exit　area　and　individuals　that　need　assistance　are　more　likely　to　be　stuck　under　this　circumstance.　Besides,　it　is　found　that　the　proper　change　of　exit　parameters　such　as　exit　position,　exit　width　and　exit　angle　can　alleviate　the　negative　effect　of　helping　behavior　on　the　evacuation　efficiency.　Furthermore,　the　motion　ability,　initial　position　and　body　size　of　difficult　person　are　also　crucial　to　the　evacuation　outcome.