Parkinson's disease (PD) is a neurodegenerative disorder and severely affects patients' daily lives. The diagnosis depends on the presence of one or more common motor symptoms of the disease. As PD is chronic and slowly progressive, the symptoms continue and worsen over a long period of time. Quantification of the PD's motor symptoms is helpful for diagnosing and monitoring patients' conditions. This paper provides approaches to quantify the motor symptoms of Parkinson's disease with wearable devices, and the quantification was developed with four paradigm maneuvers. The quantification parameters included tremor frequency, amplitude of hands movement, speed of foot-tapping and turning duration. The approach provided quantitative measures for the tremor, bradykinesia and gait symptoms, which could be useful for optimization of drug or deep brain stimulation treatments.