Disclosed is a method for determining a data rate of a user equipment (UE) for an enhanced uplink dedicated channel (EUDCH) service by a Node B in a mobile communication system having a radio network controller (RNC), the UE transmitting UE transmission power class information to the RNC, and the Node B having a table for storing total transmission power corresponding to the transmission power class, the Node B supporting the EUDCH service of the UE. The method comprises receiving uplink channel condition information of the UE from the UE, and receiving UE transmission power class information from the RNC; and reading total transmission power corresponding to the received UE transmission power class from the table, and determining a data rate of the UE considering the uplink channel condition information and the total transmission power.