Two-dimension (2D) semiconductor materials have attracted much attention and research interest for their novel properties suitable for electronic and optoelectronic applications. In this paper, we have proposed an idea in new 2D materials design by using adjacent group elements to substitute half of the atoms in the primitive configurations to form isoelectronic compounds. We have successfully taken this idea on group V monolayers and have obtained many unexplored Group IV-V-VI monolayer compounds: P2SiS, As2SiS, As2GeSe, Sb2GeSe, Sb2SnTe, and Bi2SnTe. Relative formation energy calculations, phonon spectrum calculations, as well as finite-temperature molecular dynamics simulations confirm their stability and DFT calculations indicate that they are all semiconductors. This idea broadens the scope of group V semiconductors and we believe it can be extended to other type of 2D materials to obtain new semiconductors with better properties for optoelectronic and electronic applications.