(1) Place the test tube mould into negative-pressure vacuum chamber, and form certain negative pressure inside the test tube; (2) After forming certain negative pressure, assemble the cap automatically; (3) After assembling the cap upon forming certain negative pressure inside the test tube, use the manipulator equipped with vacuum chuck to take the test tube out of the test tube mould, and then automatically install it into the foam tray; (4) The accuracy of vacuum value is high and stable, which can be set freely; (5) Adopt human-machine interface control, easy and simple to operate; (6) Both forward tray loading and oblique tray loading machines (the equipment structure of forward tray and oblique tray is different) are available as required by the user.