Tea-oil tree (Camellia oleifera Abel.) is an important edible oil woody plant with a planting area over 3,800,000 hectares in southern China. Species of Diaporthe inhabit a wide range of plant hosts as plant pathogens, endophytes and saprobes. At present, relatively little is known about the taxonomy and genetic diversity of Diaporthe on C. oleifera. Here, we conducted an extensive field survey in Hunan Province in China to identify and characterise Diaporthe species associated with tea-oil leaf spots. As a result, eleven isolates of Diaporthe were obtained from symptomatic C. oleifera leaves. These isolates were studied by applying a polyphasic approach including morphological and phylogenetic analyses of partial ITS, cal, his3, tef1 and tub2 gene regions. Two new Diaporthe species (D. camelliae-oleiferae and D. hunanensis) were proposed and described herein, and C. oleifera was revealed to be new host records of D. hubeiensis and D. sojae. This study indicated there is a potential of more undiscovered Diaporthe species from C. oleifera in China.