A memory sharing dual-mode network communication device includes a first memory, an OTT module and a PON module. The first memory is divided into an OTT region and a PON region, and the OTT module is used to obtain an OTT service, which includes an OTT processor, a memory arbitration circuit, a first memory main controller, a bridge circuit, and a memory slave controller. The PON module includes a PON processor and a second memory main controller. The memory arbitration circuit is configured to respond to a first access request from the OTT processor or a second access request of the PON processor to access the OTT area or the PON area of the first memory through the first memory host controller, and the memory arbitration circuit further determines the priority order of the first access request and the second access request.