The invention discloses an on-line editing method capable of marking pictures and a system thereof. The on-line editing system comprises a server and a user interface, wherein the user interface is connected to the server. An editing zone is established at the user interface by the server, a host node and a secondary node are established on the editing zone, pictures are inserted in the host node and are presented in the editing zone, the secondary node comprises a function description block and a line segment connected with the function description block, the line segment is connected to the inside of the picture in the host node, and the function description block can be used for editing texts and inserting pictures. When the secondary node is established, both the function description block and the line are presented on the editing zone, a user can drag the tail end of the line segment to the inside of the picture in the host node to form a mark, and thus the user can connect the host node with the secondary node quickly.