The present invention discloses a load balancing method, apparatus and system. In the present invention, a network management and control center of a basic network system interacts with a service management and control center of a network service system, and determines a load balancing policy according to entity information about service function execution entities in the network service system; and the network management and control center generates an execution flow table according to the load balancing policy, and controls a network device to perform a load balancing operation according to the execution flow table. The present invention is applicable to a network service system comprising a service function execution entity in a transparent mode, so as to implement load balancing processing on the service function execution entity in transparent mode in the network service system.