The invention relates to optical communication field, discloses a collating device and method for dynamic bandwidth in source-free optical network, and the distribution method for dynamic bandwidth is transparent, which can satisfy the requirement for different service, improve the utilization rate of bandwidth, realize the fair distribution for bandwidth, good haleness, real time, and can distribute bandwidth for different port, and support to release offline bandwidth of ONU. The distributing device for dynamic bandwidth in source-free optical network includes ascending service active fiber network unit bit-mapping register, ascending service active port bit-mapping table, ascending virtual media accessing control sub-layer information table, descending virtual media accessing control sub-layer authorization information table; said distributing device for dynamic bandwidth, consults said fiber network unit active information, port active information and length information of sending data, according to preset priority of different service, process the service flow according to priority according to preset priority, and distributes the dynamic bandwidth for ports.