Depression is one of the most important nonmotor features of idiopathic PD（Parkinson's disease ）which may not just interfere with the motor symptoms of PD but can also cause immense personal suffering as well as decreased quality of life with increased disability and caregiver burden. However,there is little hard evidence to guide clinical treatment. Although some newer dopamine agonists also have antidepressive effect, the use of tricyclic or nontricyclic antidepressants is frequently required.However, the side-effects of these agents may also worsen some preexisting nonmotor problems in PD. Wuling powder is a Chinese medicine which is made by cultivating Xylariasp mycelium using submerged fermentation technology. Xylariasp is the fungus sclerotia which grow in termite nests. Wuling powder is mainly used to soothe nerves and anti-insomnia in clinical. The antidepressant effect of Wuling powder has been confirmed in clinical, but not in the patients of Parkinson's disease. Therefore, the investigators design a randomized, double-blind, placebo-controlled study to evaluate the antidepressant effect of Wuling powder in PD patients and its underlying mechanism.

Inclusion Criteria:

1. Diagnosis of idiopathic Parkinson's disease according to the 2015 MDS（Movement Disorder Society）-PD criterion
2. Hoehn-Yahr stage: 1-3
3. Under steady therapy of antiparkinsonian drugs for at least 28 days
4. HAMD≥13
5. MMSE（Mini-Mental State Examination）≥24
6. Neither use antidepressant drugs nor antipsychotic drugs within 4 weeks
7. Signed informed consent

Exclusion Criteria:

1. Have other psychotic symptoms
2. Suicide ideation or behavior
3. Severe cognitive impairment，chronic organs failure，malignant tumors
4. Glutamic-pyruvic transaminase or glutamic oxalacetic transaminase≥1.5 times of the high normal range or white blood cell<4*10^9/L or serum creatinine>84umol/L
5. Pregnancy or lactation period
6. Participant in other trials or have taken other experimental drugs within 90 days
7. Allergic to fungal food or fungal drugs