The root rot disease of peony is one of the serious diseases. Average infected individual plant rates in old and’ new peony garden were up to 35% and about 20% respectively in the cultivation region in Heze, Shandong Province. According to the culturing characters and morphological properties of 137 isolates came from 64 infected root samples among 9 batches after selecting, purifying, re-inoculating testing, the pathogenic fungi of peony root rot disease was finally identified as the Fusariurn solani. Overwinter of pathogen mainly depended on mycelia and conidia in the root, the disease was prevalent from May to July. The occurrence of disease had a close relation with those factors including layer stubble and soil acidity and alkalinity. The Ltiheng 1,Ltiheng 2 and 50% Duofu were proved to be the effective fungicides for controlling peony root rot by laboratory toxigenicity testing and field fungicides efficacy. The control effect in new and old peony garden was about 90% and 80% respectively while the disease indices of them were controlled about 5 and 10 respectively, by applying 4 times from middle March, the pre-leafing date of peony through middle July. The paper provides a profound and systematic study on the peony root rot disease and will help to promote the development of industrialization of the peony.