NOVELTY - Preparation of nanometer modified high-efficient and low-cost polycrystalline silicon solar cell, comprises selecting the polycrystalline silicon chip; processing the fiber into fine and soft material by the fine and soft material preparing liquid, dispersing, and electrode printing.    USE - The process is useful for preparing nanometer modified high-efficient and low-cost polycrystalline silicon solar cell (claimed).    ADVANTAGE - The process can obtain the polycrystalline silicon solar cell with low reflectivity and can effectively increase the light absorbing efficiency.    DETAILED DESCRIPTION - Preparation of nanometer modified high-efficient and low-cost polycrystalline silicon solar cell, comprises selecting the polycrystalline silicon chip; processing the fiber into fine and soft material by the fine and soft material preparing liquid, dispersing, and electrode printing; where when selecting the polycrystalline silicon chip, selecting the P-type polycrystalline silicon chip with the service life of more than or equal to 40 mu s; where the electrical resistivity of the polycrystalline silicon chip is 0.5-3 Omega .cm; and the thickness is 140-200 mu m; when processing the fiber into fine and soft material by the fine and soft material preparing liquid, adopting the mixing solution of hydrogen fluoride (HF) and nitric acid (HNO3); where 0.05-0.1% of nitrogenous inorganic salt and not more than 0.1% of dispersing agent are contained in the mixing solution of HF and HNO3 by weight; and the volume ratio of the HF and HNO3 in the mixing solution is 1:2 to 1:6; cleaning the surface by the nanometer modified technology after dispersing and before electrode printing by processing the dispersed polycrystalline silicon chip by the alkaline aqueous solution containing the organic alkali and the treating compound to remove the defect and harmful impurity on the surface of the polycrystalline silicon chip; and when electrode printing, adopting the screen printing technology to print and sinter the negative electrode and positive electrode.