Defects are induced during the fabrication process of a metalens inevitably, which will affect its yield and optical performances. Thus, the investigations on the fabrication defects are becoming increasingly important for mass-production of metalenses. In this letter, optical performances of near-infrared metalenses with four types of fabrication defects are investigated. The results show that the process-induced defects affect the focusing efficiency at λ = 940 nm obviously, but have less impact on the quality of the focal spot. This work providing the fabrication guidance for the large-scale manufacturing of metalenses in future.