[Objective] The fungal conidial pigments are essential components for the formation of the fungal cell wall. The pigments play very important roles in fungal growth and resistance to various environmental stress responses. Here, the biosynthetic gene of conidial pigment was identified and characterized in Aspergillus flavus. [Methods] By the homologous search of the known pigment biosynthetic gene protein, the key gene involved in the pigment production was identified in A. flavus. The target gene was disrupted using homologous recombination strategy, and the effects of the gene deletion on fungal phenotype, sporulation, sclerotia formation, aflatoxin production, anti-ultraviolet irradiation and invasiveness were investigated. [Results] Compared with the wild-type strain, the Δpks1 mutant lost the conidial color instead of producing the white conidia. No obvious difference was detected in the growth rate, spore yield, formation of stress-resistant structure sclerotia and production of aflatoxin B₁ between WT and Δpks1 mutant strains. However, the deletion of pks1 resulted in a decrease in resistance to UV radiation and the ability to infect corn and peanut seeds. [Conclusion] The pks1 (AFLA_006170) is a key gene for conidia pigment production in A. flavus. The conidial pigment biosynthetic pathway is related to fungal resistance against UV radiation and the infection to cereal crops.