介绍了空间激光冷却原子钟地面原理样机的实验进展。该样机是以在空间微重力条件下应用为目标而研制的超高精度激光冷却铷原子钟，主要由物理单元、光学单元、微波单元和控制单元四个部分组成。该原理样机已经成功研制了空间冷原子钟所需要的超高真空系统、激光冷却光学平台、高性能微波源以及微波环形腔，实现了全过程自动运行，并获得了在地面重力条件下标志原子钟信号精度的Ramsey 条纹，确定了高精度空间冷原子钟的主要科学参数和技术指标，为进一步空间工程应用奠定了科学和技术基础。

The design of a cold atom clock in space (CACS) and its recent progress are described. The CACS is a high precision cold Rubidium atom clock for the application in microgravity environment, which has four parts, including physics, laser source, microwave source, and control system. The first CACS clock science run has been achieved as described. The essential operations of a space cold atom rubidium clock have been demonstrated in the prototype system. The key results of a clock including the ultrahigh vacuum degree, the atomic temperature， and the linewidth of the Ramsey fringes, satisfy the demands of a space cold atom clock. Based on this prototype, an engineering model for space application has been under development.