Abstract: The over the air (OTA) testing chambers for 5G base station require significant investment both in terms of space occupation and construction cost. If the in-band OTA testing requirements of 5G medium and low frequency bands and 5G millimeter wave bands are taken into account, an ultra-wide frequency range of 1.7 GHz ~71.0 GHz needs to be supported. For general far-field and compact antenna test range, both the space and cost increase dramatically. In this paper, a miniaturized OTA chamber with relatively low requirements for floor space, chamber height as well as ground load-bearing is designed, which is compatible with the ultra-wide frequency range of 5G medium and low frequency bands and millimeter wave bands, and achieves good quiet zone performance.