We have performed the systematic studies on three structurally similar aromatic molecules with different functional groups on a Cu(110) surface and investigated their on-surface molecular diffusion behaviors by the interplay of scanning tunneling microscopy imaging and density functional theory calculations. We have found that the tert-butyl groups could significantly affect the molecular adsorption geometries and moreover the mobility of the molecules on the surface. These findings could give further insights into the understanding of diffusion behaviors of organic molecules specifically with tert-butyl groups on surfaces.