A method for controlling a service performed by a policy control and charging rules function, PCRF, entity, the method comprising: • obtaining resource-related information of a cell and subscriber-related information of a user equipment, UE, in an activated state in the cell that are sent by an access network device, wherein the resource-related information includes a maximum number of UEs that the cell can serve, wherein the maximum number of UEs is defined as a Max-User-Number Attribute-Value Pair, Max-User-Number AVP, that indicates the maximum number of UEs that the cell supports (step 301); • sending a signaling for detecting, at the access network device, a cell congestion state to a policy and charging enforcement function, PCEF, entity or an operation and maintenance, OM, system or directly to the access network device to instruct the access network device to detect the cell congestion state of the cell and send cell congestion indication information of the access network device to the PCEF entity or the OM system or directly to the PCRF entity; • receiving the cell congestion indication information of the cell when the access network device detects that the cell is congested, and obtaining congestion state information of the cell according to the cell congestion indication information; • generating a quality of service, QoS, policy and/or a charging policy for the UE in the activated state in the cell according to the congestion state information of the cell, the resource-related information of the cell, and the subscriber-related information of the UE in the cell (step 302); and • sending the QoS policy and/or the charging policy to the PCEF entity (step 303). • obtaining resource-related information of a cell and subscriber-related information of a user equipment, UE, in an activated state in the cell that are sent by an access network device, wherein the resource-related information includes a maximum number of UEs that the cell can serve, wherein the maximum number of UEs is defined as a Max-User-Number Attribute-Value Pair, Max-User-Number AVP, that indicates the maximum number of UEs that the cell supports (step 301); • sending a signaling for detecting, at the access network device, a cell congestion state to a policy and charging enforcement function, PCEF, entity or an operation and maintenance, OM, system or directly to the access network device to instruct the access network device to detect the cell congestion state of the cell and send cell congestion indication information of the access network device to the PCEF entity or the OM system or directly to the PCRF entity; • receiving the cell congestion indication information of the cell when the access network device detects that the cell is congested, and obtaining congestion state information of the cell according to the cell congestion indication information; • generating a quality of service, QoS, policy and/or a charging policy for the UE in the activated state in the cell according to the congestion state information of the cell, the resource-related information of the cell, and the subscriber-related information of the UE in the cell (step 302); and • sending the QoS policy and/or the charging policy to the PCEF entity (step 303).