A method of content transmission in peer-to-peer network includes the following steps: dividing contents to be transmitted into a plurality of stripes in time sequence (101); establishing one or more than one group(s) for clients which request for transmission contents from same stripes (102); a source divides the requested content into a plurality of blocks and marks each content block (104); determining which content block will be transmitted first in an stripe requested by one group; from the determined content block beginning, transmission it and its subsequent content blocks in succession to part or all members in the group respectively (105); and controlling that the member received the content blocks from the source retransmits the content to other members in its own group (106). The invention realizes positioning play in multicast mode for the clients using a P2P technology.