CayDHT is a constant-degree structured peer-to-peer overlay network based on Cayley graph,and it is very efficient in accurate single keyword search but does not support complex searches with unrestricted form. In this paper,by analyzing the topological properties of CayDHT,a virtual tree-based complex search ( VTCS) algorithm is proposed,which needs no maintenance of the extra tree structure and can obtain the address of the next hop only according to the parameters inside the messages. Theoretical analyses indicate that the proposed algorithm can complete the search without redundant messages within O( logN) hops. Simulation results show that VTCS is more reasonable than Flooding and RW.