The present application provides a system message sending method, a system message obtaining method, a network side device, and a terminal device. The system message sending method comprises: a network side device receives a first transmission request, the first transmission request being used for requesting a first system message; if a first preset condition is satisfied, sending the first system message in a broadcast and/or multicast manner; and if the first preset condition is not satisfied, the network side device unicasts the first system message. By using the method, the network side device and the terminal device provided in the present application, information amount of the unicast can be greatly reduced, thereby reducing the waste of radio resources.
