A fluid collector unit of a wound drainage therapy system includes a multiple-pipe integration module and a collection bag. The multiple-pipe integration module includes first, second and third connection ports. The collection bag includes a negative-pressure buffer zone and two fluid collection zones that communicate with each other. The negative-pressure buffer zone is located between the two fluid collection zones and isolated from the two fluid collection zones. The two fluid collection zones are connected with the first connection port of the multiple-pipe integration module. The negative-pressure buffer zone is connected with the second and third connection ports of the multiple-pipe integration module, and the negative-pressure buffer zone has a fluid input port.