The invention discloses a laser one-step forming method for a surface nap layer and an isolation layer of a crystalline silicon solar cell. The laser one-step forming method comprises the steps as follows: 1, cleaning a crystalline silicon sheet; 2, preparing the surface nap layer: scanning the surface of the crystalline silicon sheet by utilizing a laser source focused by a lens in the atmosphere of argon, and forming the surface nap layer with silicon fine grains and micro pits; and 3, preparing the isolation layer: synchronously conveying oxygen, continuously scanning the edge of black silicon by the laser source to obtain the silicon dioxide isolation layer. The laser one-step forming method has the benefits that the surface nap layer and the isolation layer can be formed in one step; the surface nap layer can be prepared only in the atmosphere of the argon, the condition is easy to satisfy, and the light reflectivity of a wave band of 250-1,050 nm of the obtained surface nap layer is less than 10 percent; a novel structure of the crystalline silicon solar cell, that has the surface nap layer and the isolation layer which are on the same surface layer, is disclosed, and the prepared isolation layer improves the utilization ratio of the surface nap layer; and the preparation of the surface nap layer and the isolation layer only relates to the argon and the oxygen, so that the method is environmental-friendly.