Abstract: The link in space delay-tolerant network is inter-contacted, which makes it impossible to form a end-to-end path. So data transmission mechanism by end-to-end based on TCP/IP can not be adjusted to space delay-tolerant network. In the space delay-tolerant network, there are large number of satellite nodes, which are shortly and periodical connected, and run very fast in periodical movement. They consist of the core link in space-to-ground and space-to-space. Toward the periodical contact links in space delay-tolerant network, the periodical contact time of a satellite to land and contact time of links between satellites are computed based on the analysis of moving regulation of satellites. The data forwarding algorithm based on contact vector between nodes is designed. This algorithm solves the problem of data effective forwarding in periodical links of space network in effect. The simulation results show that this algorithm has better performance on delivery successful rate and transmission delay in periodical links.