Abstract: SaaS provides complete software application services to different users in the endpoint of cloud.In SaaS application,cloud database should not only provide the storage and retrieval of massive data,but also be able to customize data structure easily for different users.A tree cloud database is proposed in this paper.This database organizes and searches data by a strucure of tree.The type of node in the tree includes number,characters,text,two-dimensional tables,file and so on.The time complexity of search at the worst case is o[log2/N].The existed data in table and file could be reorganized easily to the tree structure in order to meet the storage and retrieval requirements of SaaS.