The conduction of nano-scale titanium oxide memristor exhibits complex characteristics, owing to the change of self-parameters and the coexistence of different conductive mechanisms. However, there has been no detailed discussion about the influence of the cross section area change on the conductive characteristics of memristor. Based on dopant drift and tunnel barrier mechanisms, the conductive process of memristor is analysed, and the relevance between cross section area and key physical factors of the conductive process is studied, then the influences of the changes of titanium oxide and tunnel barrier cross section area on conductive characteristics of memristors are studied, respectively. The differences and connections between the two cases are analysed. In the case of the coexistence of those two mechanisms, compared with the change of titanium oxide cross section area, the change of tunnel barrier cross section area is proved to be the chief factor which causes changes of memristor conductive characteristics, it is also a possible factor causing the change of non-ideal conductive characteristics of memristor. The research results contribute to further explaining the complexity of memristor conductions and providing basis for optimizing memristor modeling.