The invention provides a preparation method for preparing a uniform-nature horizontal array for an overlong single-wall carbon nano-tube by utilizing a stable airflow and a reaction device and relates to the field of nano-material research. The preparation method comprises the following steps: reducing a catalyst precursor in a reducing atmosphere into a catalyst with an activity and then quickly reducing the temperature to non-reaction temperature; placing both a second substrate and a first substrate loaded with the catalyst with the activity into a stable laminar flow atmosphere with a carbon source; quickly increasing the temperature to the growth temperature and reacting, thus obtaining the horizontal array for the overlong single-wall carbon nano-tube. The reaction device at least comprises a reaction chamber and a heating device. The reaction chamber can quickly increase temperature and reduce temperature so as to meet the temperature requirement required by the reaction. The method and the device provided by the invention can guarantee the aligned parallel array of the acquired overlong single-wall carbon nano-tube in stable laminar flow and can effectively controllable prepare the horizontal array for the overlong single-wall carbon nano-tube with flawless surface, uniform nature, high collimation, high parallel property and high density.