The invention relates to a network voice communication method and a network voice communication system based on a webpage communication plug-in. The network voice communication system comprises the webpage communication plug-in, a webpage real-time communication SIP server, a network voice communication SIP server and a called party answering terminal, wherein the webpage communication plug-in is used for establishing a call stream communication channel with the called party answering terminal for making a call, the webpage communication plug-in is embedded into a webpage, and the webpage communication plug-in is internally provided with a call button assembly and a hang-up button assembly; the webpage real-time communication SIP server is used for establishing webpage real-time communication connection between the webpage communication plug-in and the called party answering terminal; the network voice communication SIP server is used for establishing webpage real-time communication connection between the webpage real-time communication SIP server and the called party answering terminal; and the called party answering terminal is used for establishing a call stream communication channel with the webpage communication plug-in to make a call with a caller party. The network voice communication method and the network voice communication system realize the effect that the caller party can communicate with the called party without downloading and installing a client or a plug-in.