To understand the major diseases and insect pests in the cut-log cultivation of Ganoderma sinense under forest in mountainous areas of northern Guangdong, and to develop corresponding prevention and control measures. From 2022 to 2024, the diseases and insect pests in the cut-log cultivation of G. sinense under forest in the mountainous area of northern Guangdong were continuously investigated, and the types and characteristics of pests and diseases were analyzed according to the climatic conditions and cultivation management. The result shows that, the climatic characteristics of rain and heat at the same period in the mountainous area of northern Guangdong easily lead to the overlapping damage of fungi and other diseases and insect pests in the growth period of the G. sinense under the forest, and the main diseases included Trichoderma viride, Myxomycetes and other competitive macrofungi, among which T. viride has high occurrence frequency and most serious harm. Termites, larvae of Diomea spp. and Limax spp. are the main insect pests, among which termites are the most harmful to wood fungus sticks of G. sinense. The larvae of Diomea spp. mainly harms the growth stage fruit body of G. sinense, while the damaged fruit body is easy to be infected by fungal diseases. The species and occurrence of major diseases and insect pests in the cut-log cultivation of G. sinense under forest in the mountainous area of northern Guangdong were found out, and the prevention and control measures were proposed.