Valsa mali var. mali is the causal agent of apple tree canker disease, causing severe economic losses in major apple production areas in China. To better understand the infection mechanisms of V. mali and plant-pathogen interactions, the pathogen was genetically transformed with enhance green fluorescence protein (EGFP) as a vital marker using Agrobacterium tumefaciens-mediated method. The average transformation efficiency was 675.00±20.61 transformants per 106 recipient conidia, and transformants showed mitotic stability and EGFP expression. This is the first successful transformation of V. mali with EGFP expression, allowing hyphal visualization in vivo.