Embodiments of the present invention provide a resource allocation method and device for direct communication between user devices. The method includes: determining, by a third device, a first resource, where the first resource includes some or all of a second resource, the second resource is determined by the third device before the first resource is determined, and the first resource and the second resource are both used for communication between a first user device and a second user device; and sending, by the third device, resource signaling to the first user device and/or the second user device, where the resource signaling carries information about the first resource. When a resource for direct communication changes, a normal direct communication service of user devices is ensured.
