A solar cell, characterized by comprising: an N-type substrate; a P-type emitter formed on a first surface of the N-type substrate, wherein the P-type emitter comprises a first portion and a second portion, first pyramid structures are formed on a top surface of the first portion, and second pyramid structures are formed on a top surface of the second portion, wherein a transition surface is respectively formed on at least one edge of each first pyramid structure, the transition surface is joined with two adjacent inclined surfaces of the each first pyramid structure, and the transition surface is concave or convex relative to a center of the each first pyramid structure, wherein a substructure is formed on each of top surfaces of at least a part of the first pyramid structures, and a shape of the substructure is spherical or spherical-like, wherein edges of each second pyramid structure are straight, and wherein a sheet resistance of the first portion ranges from 10 ohm/sq to 500 ohm/sq, a doping concentration at the top surface of the first portion ranges from 1E 17 atoms/cm 3 to 8E 19 atoms/cm 3, a sheet resistance of the second portion ranges from 100 ohm/sq to 1000 ohm/sq, and a doping concentration at the top surface of the second portion ranges from 1E 16 atoms/cm 3 to 5E 19 atoms/cm 3; a tunnel layer and a doped conductive layer sequentially formed over a second surface of the N-type substrate in a direction away from the N-type substrate; and a first metal electrode formed on the first surface of the N-type substrate, wherein the first metal electrode is electrically connected to the first portion of the P-type emitter. an N-type substrate; a P-type emitter formed on a first surface of the N-type substrate, wherein the P-type emitter comprises a first portion and a second portion, first pyramid structures are formed on a top surface of the first portion, and second pyramid structures are formed on a top surface of the second portion, wherein a transition surface is respectively formed on at least one edge of each first pyramid structure, the transition surface is joined with two adjacent inclined surfaces of the each first pyramid structure, and the transition surface is concave or convex relative to a center of the each first pyramid structure, wherein a substructure is formed on each of top surfaces of at least a part of the first pyramid structures, and a shape of the substructure is spherical or spherical-like, wherein edges of each second pyramid structure are straight, and wherein a sheet resistance of the first portion ranges from 10 ohm/sq to 500 ohm/sq, a doping concentration at the top surface of the first portion ranges from 1E 17 atoms/cm 3 to 8E 19 atoms/cm 3, a sheet resistance of the second portion ranges from 100 ohm/sq to 1000 ohm/sq, and a doping concentration at the top surface of the second portion ranges from 1E 16 atoms/cm 3 to 5E 19 atoms/cm 3; a tunnel layer and a doped conductive layer sequentially formed over a second surface of the N-type substrate in a direction away from the N-type substrate; and a first metal electrode formed on the first surface of the N-type substrate, wherein the first metal electrode is electrically connected to the first portion of the P-type emitter.