The effective plasma frequency fp of periodic metallic wires whose characteristic dimensions are comparable to their skin depth has been analyzed. And a relevant analytic model is constructed by considering the skin effect and making a reasonable shape approximation, which is suitable for the case that the cross section of the wire is noncircular. To verify this model, a wires array with rectangle cross section is designed and the corresponding stacked Au-SiO(2) nanostrips are fabricated. The experimental and simulational transmittances of the metamaterial have been evaluated with a good agreement, although the presence of quartz substrate and structural imperfections in experiment will have an impact, which validates that the multilayer Au-SiO(2) nanostrips could function similarly to a natural bulk metal with discrepancies of fp values less than 8%. It could be confirmed that the theoretic formula is trustworthy in predicting fp for designing and realizing a controllable artificial metal in optical region.