The Lower Cretaceous Guantou Formation is considered as one of the few and significant horizons hosting Cretaceous petrified fossil woods in southern China. This study reports a wellpreserved petrified wood with fungal infection found in the Guantou Formation in Xinchang, Zhejiang Province. Anatomically, the fossil wood is characterized by distinct growth rings (araucarian radial pitting, araucarioid crossfield pits, and uniseriate xylem rays). The fossil wood from Xinchang has similar anatomical characters as the extant Araucariaceae, and thus can be referred as to the genus Agathoxylon Hartig. Considering that the identification of Agathoxylon at species level is confused and problematic, the new fossil wood material is tentatively ascribed as Agathoxylon sp. Wellpreserved fungal remains, represented by fungal hyphae with typical clampconnection, were found within the fossil wood tissue. The occurrence of clampconnection indicates that the fungal remains systematically belong to the Basidiomycota. The typical wood decay feature of the wood fossil resembles that of the extant whiterot, indicating that the current fungal remains should be whiterotting fungi. The finding of Agathoxylon sp. in the XInchang region further enriches the fossil wood diversity of the Guantou Formation, improving our understanding of the composition features of the Early Cretaceous fauna in southern China. The fungal remains represent the first record of the Cretaceous wood rotting fungi in southern China, and provide new fossil evidence for revealing the plantfungal interaction in the Early Cretaceous forest ecosystem.