The invention provides an online displaying method and device for electronic files. The method comprises the following steps: receiving a current page reading request, which is transmitted by a user through a terminal, of an electronic file, wherein the current page reading request comprises electronic file page identification; determining a current page, which corresponds to the electronic file page identification, of the electronic file; converting the current page of the electronic file into an SWF file; transmitting the SWF file to the terminal so that the SWF file is displayed on the terminal. The user can request a certain page of the electronic file required to be read according to self demands, and then the current page, which is converted into the SWF file, of the electronic file is transmitted to the terminal; the user can conveniently read the electronic file according to self demands; and meanwhile, the electronic file does not require to be displayed page by page by a server through the terminal, memory resources of the server and the terminal are saved, and the displaying speed of the electronic file is increased.