Abstract: Based on the vague relational data model and vague similarity measure as shown in earlier works, the vague data dependencies on database are investigated. The definitions of vague functional dependencies (VFDs) and vague multivalued functional dependencies (VMVDs) are both given, as well as the inference rules corresponding to them, which are similar to Armstrong's axioms of the VFD and VMVD in classical relational database and named the vague axioms. The effectiveness and completeness of vague axioms are proved with the idea about the satisfiability of VFDs and formula to calculate the satisfiability both given.