Abstract: Cold gas is the raw material that collapses and forms new stars in galaxies, thus it plays a crucial role in galaxy evolution. Understanding what drives the cold gas fraction in galaxies and how gas kinematics evolve with cosmic time are fundamental quests for a complete view of galaxy evolution. I will present recent studies of cold gas in high-redshift galaxies, including how to probe the rise and fall of cold gas fraction evolution, how to trace the evolution of gas depletion time, and how to understand galaxy kinematics’ evolution in the hierarchical Universe. I will highlight our work named the Automated Mining of the ALMA Archive in COSMOS (A3COSMOS) project, where we utilize hundreds of hours of public ALMA archival observations to obtain statistical knowledge of galaxy evolution. The A3COSMOS project has led to the constraining of cold gas scaling relations and cosmic molecular gas density evolution from redshift z~0-6 and has become a useful resource for the community. I will also highlight the recent studies of cold and ionized gas kinematics in high-redshift galaxies, where modern rest-frame optical IFU studies at cosmic noon and (sub)millimeter interferometric studies in z~2-5 starbursts show worrisome controversial results. I will summarize the talk with the current understanding of the ‘paradigm’ in galaxy evolution, which has been established over the last two decades but is also facing new challenges.