This communication reports a strategy for solid surface-mediated DNA self-assembly. DNA molecules weakly interact with solid surfaces; thus are confined to solid surfaces. The confinement reduces the flexibility of DNA nanomotifs and promotes the DNA 2D crystals to grow on solid surfaces. As a demonstration, periodic DNA nanoarrays have been directly assembled onto mica surfaces. Such in situ assembly eliminates the sample transfer process between assembly and characterization and possible applications.