Microlens arrays are the key component in the next generation of 3D imaging system,for it exhibits some good optical properties such as extremely large field of view angles,low aberration and distortion,high temporal resolution and infinite depth of field.Although many fabrication methods or processes are proposed for manufacturing such precision component,however,those methods still need to be improved.In this review,those fabrication methods are categorized into direct and indirect method and compared in detail.Two main challenges in manufacturing microlens array are identified:how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested.Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning.Finally,the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.