Molecular beam epitaxy growth of lattice mismatched InAs/GaAs(001) system is studied by in situ scanning tunneling microscopy (STM) and reflection high energy electron diffraction. We found that deposition of submonolayer (similar to 0.6 ML) In on the GaAs(001)-As-rich 2 x 4 surface could result in a new well-ordered 4 x 2 reconstruction? and that if the growing front maintains this reconstruction, the multilayer InAs will grow two-dimensionally and usually observed 3D islanding is completely suppressed. Atomic structures for the 4 x 2 reconstruction are discussed on the basis of voltage-dependent STM image. A "domain wall" structure, representing a new type of surface strain relief mechanism in the novel growth will also be discussed.