The invention discloses a preparation method of a surface micro and nano composite structure of a monocrystalline cell. The preparation method comprises the following steps: S1, alkali texture surfacemaking: forming a pyramid textured surface with the reflectivity being 15-17%, wherein the size of a pyramid is 5-10 mu m; S2, primary acid pickling: carrying out acid pickling by using a HNO3 solution, wherein the concentration of the HNO3 solution is 0.5-1%, the temperature is a normal temperature, and the acid pickling time lasts for 60-100 s; and S3, silver ion auxiliary texture surface making: forming nano pits of which the diameters are 80-130 nm and the depths are 150-200 nm. Conventional monocrystal alkali texture surface making is combined to conventional black silicon silver ion auxiliary texture surface making, texturing on the surface of monocrystalline silicon is realized to form a micro-nano composite-structured textured surface, while the low reflectivity is ensured, the specific surface area is small, surface compounding is relieved, the cell conversion efficiency is further improved, the practicality is quite high, and thus, the preparation method is quite worthy of being popularized.