The invention discloses a microblog forwarding tree and forwarding forest building method, and belongs to the field of data mining. The microblog forwarding tree and forwarding forest building method comprises the following steps that original microblog information of a microblog is collected; in addition, the forwarding microblog information is obtained according to the single piece of original microblog information; then, a microblog tree structure of the single piece of microblog is built on the single piece original microblog information and all forwarded microblog information; total microblog information relevant to the topic is collected according to the topic keywords Topic in a user given time period t3 to t4, and the microblog tree structure of the single piece microblog is built by aiming at each piece of microblog information; finally, the forwarding trees of the total microblog information relevant to the topic is summarized; a microblog forwarding forest is formed. The microblog forwarding tree and forwarding forest building method has the advantages that through a forwarding tree generating algorithm, the forwarding tree and forward forest extraction is efficiently fast and completely carried out, and higher efficiency and effects are realized.