A　multi-round　scheduling　algorithm,　data-collection　multi-round　(DCMR),　is　presented　to　minimize　the　makespan　of　divisible　workloads　in　parallel　computing.　A　three-stage　model　is　proposed　and　takes　communication　latency　and　computation　start-up　time　into　consideration.　The　algorithm　provides　a　method　to　generate　a　near-optimal　number　of　scheduling　rounds.　Close-form　equations　are　given　through　analyzing　a　specific　time　sequence　of　load　distribution,　and　then　the　bisection　method,　combined　with　back-forward　adjustment,　is　used　to　get　an　asymptotically　optimal　number　of　scheduling　rounds,　which　make　the　computation　time　overlap　the　communication　time　as　much　as　possible　and　reduce　the　makespan.　Simulation　results　show　that　the　algorithm　can　find　a　near-optimal　number　of　scheduling　rounds　under　different　network　parameters.　Compared　with　the　classical　algorithms　such　as　FIFO　and　LIFO,　the　DCMR　has　higher　adaptability.　When　the　computation　time　dominates　the　communication　time,　the　algorithm　can　keep　the　makespan　at　a　rather　low　level　which　is　about　1.1　times　of　the　ideal　time.