The present invention discloses a method for ensuring service classes of packet services, which includes limiting the rate of services with different service classes uploaded to a ringlet from an RPR station in accordance with the RPR physical packet lengths; monitoring, in real time, the rate of non-class A0 services uploaded to the ringlet from the RPR station and forwarded by the RPR station in accordance with the RPR physical packet lengths, and when the rate of the non-class A0 services exceeds the un-reserved rate of the RPR network, reporting a congestion message and adjusting the rate of the non-class A0 services uploaded to the ringlet from the RPR stations in the congestion domain. A method of rate limitation is also disclosed, by which rate limitation is conducted based on a Token Bucket according to the total length of the sent packet after encapsulation. The methods, by means of rate limitation and rate monitoring of the services uploaded to the ringlet from each RPR station according to the RPR physical packet length, can effectively overcome the shortcoming that the reserved bandwidth in the RPR can not be ensured because forwarded services unexpected occupy the bandwidth of the services uploaded to the ringlet at a downstream RPR station due to the physical layer encapsulation overhead.