As a new generation of display technology, microLED demonstrates the advantages of high brightness, low energy consumption, long life, and selfluminous. However, the technical bottlenecks, such as difficulties in achieving highefficiency fullcolor displays, have hindered their industrialization processes and popularity. The fullcolor display is a crucial technology for the commercialization of microLED. However, with the high degree of integration and miniaturization of LED chips, the mass transfer of RGB chips to the same substrate for achieving fullcolor display has resulted in high costs and low yields. Therefore, there is an urgent need to discover a simpler and more efficient method for fullcolor display. This paper provides an overview of microLED microdisplay device fabrication technologies and several methods for achieving fullcolor displays, focusing on the quantum dots color conversion layer method, the RGB direct alignment method, the special structure method, and the optical lens method. The technical challenges and development trends of microLED microdisplays are also discussed.