The invention discloses a session method and system of a system platform based on a web page and an electronic device; wherein the method comprises following steps of receiving a first invoking request initiated by the system platform side based on the web page, wherein login information of a session initiator and/or attribute information of a session receiver is carried in the first invoking request; invoking a preset session tool according to the first invoking request, wherein the preset session tool comprises a web session tool based on the web page and/or an independent client session tool; displaying the attribute information of the session receiver at the invoked preset session tool side; sending the session message to the corresponding session window of the session receiver side through the invoked preset session tool, wherein the session window is the instant session window loaded in third party software. Through adoption of the method, the system and the electronic device, the problem of low session efficiency is solved.