Communication control method in local area network, communication master device and system

The invention discloses a communication control method in a local area network, a communication master device and a system, and the method comprises the steps: transmitting a broadcast search instruction to each slave device for device search at an interval of a first preset time length, so that each slave device randomly generates a first timing time slice after receiving the broadcast search instruction, responding to the search instruction after the timing of the first timing time slice is finished; after the device search is finished, sending a broadcast access instruction to each slave device, so that each slave device randomly generates a second timing time slice after receiving the broadcast access instruction, and responds to the access instruction after the timing of the second timing time slice is finished; and after the equipment access is finished, the master equipment sends a synchronization instruction to each slave equipment, so that each slave equipment randomly generates a third timing time s