Machine-picked cotton has been the main cotton planting mode in China, especially in the main cotton producing areas. Cotton pickers are key equipment for harvesting machine-picked cotton and are also typical representatives of high-end agricultural machinery. Starting from the operation process and principle of cotton pickers, the literature on unginned cotton picking, unginned cotton collection and transportation, unginned cotton compression and packaging, chassis driving and walking, and intelligent control of the whole machine were introduced, and the topics, difficulties, problems, and shortcomings of current research were analyzed. After the development of government guidance and free market competition, the research, development, and manufacturing systems of cotton pickers have been formed in China, based on the introduction, digestion and absorption of foreign advanced technologies. However, there were still some basic scientific problems in cotton pickers, such as the blocking mechanism of the picking head, the dynamic evolution of the pneumatic conveying flow field, and the chassis load spectrum, which have not been solved. The structural design schemes such as the baling mechanism were not innovative and original enough and were still subject to foreign patents. The operation status monitoring and intelligent operation levels were high, but there was a lack of high-precision special sensors such as unginned cotton flow, cotton bale density/humidity. In view of the above problems and shortcomings, the future research direction was analyzed and prospected from the aspects of unginned cotton picking mechanism, high-fidelity simulation analysis of pneumatic conveying, dynamic analysis and optimization of walking chassis, innovative design of baling mechanism, and intelligent control, which can provide reference for the optimization and design, production and manufacturing, and the control of cotton pickers.