A dynamic bandwidth allocation method for an uplink system of an Ethernet passive optical network (EPON), comprising: acquiring actual traffic of an optical network unit according to a bandwidth request value reported by the optical network unit and a bandwidth value allocated and issued to the optical network unit; and adjusting the bandwidth value allocated to the optical network unit according to the acquired actual traffic of the optical network unit, characterized in that the acquiring the actual traffic of the optical network unit according to the bandwidth request value reported by the optical network unit and the bandwidth value allocated and issued to the optical network unit comprises: in response to that the bandwidth request value reported by the optical network unit in an (n-1)-th cycle comprises the bandwidth value issued in the (n-1)-th cycle, serving a difference between the bandwidth request value reported by the optical network unit in the (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle as the actual traffic of the optical network unit, wherein the adjusting the bandwidth value allocated to the optical network unit according to the acquired actual traffic of the optical network unit comprises: adjusting the bandwidth value issued in an n-th cycle to a value acquired by a difference between the bandwidth request value in an (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle, and wherein n is a natural number greater than or equal to 1. acquiring actual traffic of an optical network unit according to a bandwidth request value reported by the optical network unit and a bandwidth value allocated and issued to the optical network unit; and adjusting the bandwidth value allocated to the optical network unit according to the acquired actual traffic of the optical network unit, characterized in that the acquiring the actual traffic of the optical network unit according to the bandwidth request value reported by the optical network unit and the bandwidth value allocated and issued to the optical network unit comprises: in response to that the bandwidth request value reported by the optical network unit in an (n-1)-th cycle comprises the bandwidth value issued in the (n-1)-th cycle, serving a difference between the bandwidth request value reported by the optical network unit in the (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle as the actual traffic of the optical network unit, wherein the adjusting the bandwidth value allocated to the optical network unit according to the acquired actual traffic of the optical network unit comprises: adjusting the bandwidth value issued in an n-th cycle to a value acquired by a difference between the bandwidth request value in an (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle, and wherein n is a natural number greater than or equal to 1. in response to that the bandwidth request value reported by the optical network unit in an (n-1)-th cycle comprises the bandwidth value issued in the (n-1)-th cycle, serving a difference between the bandwidth request value reported by the optical network unit in the (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle as the actual traffic of the optical network unit, wherein the adjusting the bandwidth value allocated to the optical network unit according to the acquired actual traffic of the optical network unit comprises: adjusting the bandwidth value issued in an n-th cycle to a value acquired by a difference between the bandwidth request value in an (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle, and wherein n is a natural number greater than or equal to 1. adjusting the bandwidth value issued in an n-th cycle to a value acquired by a difference between the bandwidth request value in an (n-1)-th cycle and the bandwidth value issued in the (n-1)-th cycle, and wherein n is a natural number greater than or equal to 1.