The invention relates to a long-acting benserazide sustained release microsphere composition. The composition comprises the following components in percentage by weight: 40 to 99 percent of degradable hydrophobic polymer and 1 to 60 percent of benserazide. The invention also provides a preparation method for the long-acting benserazide sustained release microsphere composition. The composition overcomes the defects of the conventional single oral administration scheme, administration loss of people with the disease due to the requirements of frequent oral administration, and ineffective treatment. The invention provides the preparation method using one W/O/W. The particle diameter of the composition can be controlled according to different needs and the composition does not pollute environment; and influences on the treatment effect of the benserazide can be avoided. The particle diameter can be adjusted and controlled to be between 1 mu n and 500 mu n according to needs. The freeze-drying powder of the composition is white, delicate and loose, does not collapse and conglutinate and has good dispersibility. Compared with an oral preparation of the same dosage, the composition is obviously better than the oral preparation in effect.