The invention provides a method for manufacturing a CZTS solar cell, which comprises the following steps: (A) a substrate is cleaned; (B) a back electrode layer is sputtered; (C) a precursor layer ismanufactured through co-sputtering according to a ratio of the number of atoms of the Cu to the number of atoms of Zn and Sn of 0.6-0.95 and a ratio of the number of the atoms of Zn to the number of atoms of Sn of 0.7-1.3; (D) the substrate containing the precursor layer is placed in an inert gas atmosphere at a temperature of 570 -630 degrees centigrade for vulcanization treatment so as to obtaina CZTS thin film; (E) the substrate containing the CZTS thin film is heated to the temperature of 400 -500 degrees centigrade by magnetron sputtering, and a CdS buffer layer with the thickness of 25-45 nm is sputtered on the CZTS thin film, so that heat treatment is performed on the substrate containing the CdS buffer layer for 5 -15 minutes at the temperature of 400 -500 degrees centigrade; (F)an intrinsic zinc oxide layer with the thickness of 30 -80 nm is manufactured; (G) an aluminum-doped zinc oxide layer with the thickness of 300 -500 nm is manufactured; (H) a grid electrode layer with the thickness of 1 -3 microns is manufactured. The method has the advantages that the manufacturing process is simple, and the uniformity of components of the battery absorbing layer, the diode quality factor and the conversion efficiency can be greatly improved.