Parkinson disease (PD) is an insidious and progressive neurodegenerative disease. It is the second most common neurodegenerative disease affecting 1%-3% of the population over the age of 65. While the etiology of PD is complex, α-synuclein (α-syn) misfolding and aggregation is identified as the hallmark of PD. Due to lack of the reliable biomarkers, early diagnosis of this disease is difficult. In this review, we discuss recent research progresses in the development of PD biomarkers based on the detection of α-synuclein from different samples, including body fluids (cerebrospinal fluid, blood, saliva) and peripheral tissues (skin, olfactory mucosa, salivary gland, gut mucosa). Furthermore, we summarize the recent advances on the therapeutic approaches targeting α-synuclein in treating PD.