Searching for the neutrinoless double beta ($0\nu\beta\beta$) decay is a promising way to probe the Majorana nature of neutrinos and provide insight into beyond Standard Model physics which might solve the matter-antimatter asymmetry in our current Universe. The China Dark matter EXperiment (CDEX) collaboration is planning and constructing a next-generation $0\nu\beta\beta$ experiment (CDEX-300$\nu$) to search for the 0𝜈𝛽𝛽 decay of $^{76}$Ge in China Jinping Underground Laboratory (CJPL). CDEX-300$\nu$ will use about 225 kg $^{76}$Ge enriched germanium detectors coupled with passive and active background suppression technologies to conduct a "background free" search for the $^{76}$Ge 0$\nu\beta\beta$ decay signal. The target $^{76}$Ge $0\nu\beta\beta$ decay half-life sensitivity of CDEX-300$\nu$ is 10$^{27}$ yr with one ton-yr exposure at a background level of 10$^{-4}$ counts/(kg·keV·yr) in the signal region, corresponding to a effective neutrino mass of 28.5-68.0 meV ranging by the uncertainty of the nuclear matrix element. In this paper, we present $0\nu\beta\beta$ search efforts from CDEX and the preconceptual design of the CDEX-300$\nu$ experiment.