A novel structure,named vectorial service lattice(VSL),is proposed to organize Web services by combining the theory of concept lattice and the properties of Web services.An operation vector can be extended by introducing the operation vector concept gained from the corresponding VSL.Based on the extended operation vector,an approach for service retrieving is presented.Some useful concepts,such as operation vector,context of operation vector and kdimensional operation vector,are proposed.Experimental results show that retrieving Web service based on VSL is of good performance.