The embodiments of the present disclosure provide a bandwidth assignment method and apparatus, and a bandwidth check method and apparatus. Specifically, the bandwidth assignment method includes that: first relevant information about a bandwidth assigned to an Optical Network Unit (ONU) is obtained, wherein the first relevant information at least includes service control signaling in a bandwidth-related protocol packet; and the first relevant information is converted into first bandwidth information, and a bandwidth is assigned to the ONU according to the first bandwidth information, wherein the first bandwidth information includes: a bandwidth size corresponding to the bandwidth assigned to the ONU, a delay corresponding to the bandwidth assigned to the ONU, and a start time corresponding to the bandwidth assigned to the ONU. By means of the embodiments of the present disclosure, the problem in the related art of the difficulty of a Passive Optical Network (PON) system in meeting the transmission delay requirements required by a mobile service is solved, thereby achieving the effect of reducing the transmission delay of the PON system.