The invention discloses a system for realizing communication based on an existing WiFi network. The system is composed of a WiFi intercom terminal, a WiFi wireless network and a WiFi intercom management platform, wherein the WiFi intercom terminal uses the wide area network WiFi access technology, and is connected to the WiFi intercom management platform through any global AP hotspot so as to realize the WiFi voice intercom function. As long as there is the WiFi network, WiFi intercom terminals can achieve local and cross-region wireless intercom, and the frequency point cost and call cost arenot needed to be paid, full duplex communication can be realized easily, and the voice is very clear. Further, a video data upload function can be realized by using a terminal with a screen. The system of the invention has simple system architecture, fast arrangement, powerful function and low cost, and can be widely used in star hotels, large-scale hospitals, medical examination centers, large malls and supermarkets, large warehouses, sports centers, airport ground services, catering enterprises, production enterprises, security duty, substation routing inspection and other scenes.