In this talk I will introduce the historical developments of CMB experiments in the past decades. Thanks to the great developments in the CMB surveys, we have gradually stepped into the era of precision cosmology. By virtue of the high precision data, we are able to distinguish a number of theoretical modes that were designed to describe the physics of very early universe. I will give a brief description of inflationary and bounce cosmologies, and report on the recent observational constraints upon these models. After that, I will introduce the latest progress of the Ali Cosmic Polarization Telescope project.