The invention provides a semi-automatic assembly machine for a precision valve. The machine comprises a positioning press component (2), a positioning fixture component (3) and an electrical component (4). The positioning press component (2) comprises a valve positioning component and a press component. The press component comprises a bracket, a press cylinder (17), a press bar (18), a lift cylinder (21) and a first linear guide rail (14). The valve positioning component is located below the press cylinder. The valve positioning component comprises a fixation frame, a preload component and a three-jaw cylinder (33) in a hollow structure. The positioning fixture component is located below the valve positioning component. The positioning fixture component comprises a large platen (41), a fixture carrier plate (40) and a fixture push cylinder (35). The electrical component is used for driving the press cylinder, the lift cylinder, the three-jaw cylinder and the fixture push cylinder to move. The semi-automatic assembly machine provided by the invention has the advantages of high assembly efficiency, reduced assembled product defective rate and simple and convenient operation.