Due to The Qt Company offering changes, open source offline installers are not available any more since Qt 5.15. Read more about offering changes in the https://www.qt.io/blog/qt-offering-changes-2020 blog.
If you need offline installers, please consider our new Qt for Small Business offering: https://www.qt.io/blog/available-now-qt-for-small-businesses
所以只能下载 QT 5.14 的开发环境安装文件
Index of /archive/qt/5.14/5.14.2
Windows 环境建议使用 MSVC 编译器，需要下载和安装 Visual C++ 生成工具（Buildtools）。QT 5.14 最高支持 MSVC2017，所以需先下载和安装 Visual C++ 2017 生成工具，然后再安装 QT 5.14。
Visual C++ 2017生成工具下载：
https://my.visualstudio.com/Downloads?q=2017
