We put forward a utility algorithm on fairness metrics for EPON.By building an ACK compression and decompression mechanism based on ACK-specialized packet

we reduce the ACK interference of upstream ONU on downstream ones

the fairness between ONUs is not only ensured

but also the bandwidth efficiency is increased.By presenting a utility classifier

we improve the fairness among parallel user traffics while keeping the expansibility of priority mechanism.By introducing a delay-fairness scheduling mechanism

we reduce the delay unfairness among a ONU priorities when the bandwidth is not reduced.