The quality of molecular‐beam epitaxy (MBE) growth GaAs–AlGaAs are essential for the properties of new type microstructural devices. Improved growth conditions in MBE have permitted the fabrication of high‐quality ultrathin microstructural materials. In this paper, we report the preparation of MBE grown high‐quality GaAs–AlGaAs quantum wells (QW’s) and their properties. The 1.2 meV FWHM ofE1hindicates the high quality of the material. Growth conditions (especially growth temperatureTsand precise control of the layer thickness) and the substrate preparation are important factors for MBE growth of high‐quality ultrathin microstructural materials. The molecular‐beam sources of our MBE system are vertical type Knudsen cells employing PBN crucibles. Entire component parts of our MBE system were made in China.