The invention discloses a preparation method of an iodide ionic ligand PbS nanocrystal, iodide ionic ligand PbS nanocrystal ink and a solar battery. According to the preparation method, a Pbs nanocrystal passivated by a iodide ionic ligand is synthesized directly at one step under the action of butyl amine by taking lead iodide and N,N-thiocarbanilide as precursors and taking N,N-dimethyl formamide as a solvent, so that the preparation process flow is simplified, and the synthetic preparation cost and device preparation cost of the nanocrystal are lowered. The iodide ionic ligand Pbs nanocrystal provided by the invention can be dissolved in N,N-dimethyl formamide and other solvents to obtain iodide ionic ligand PbS nanocrystal ink of which the nanocrystal absorption peak is adjustable within a range of 850 to 1100 nanometers. Meanwhile, when a N,N-dimethyl formamide solution of the PbS nanocrystal passivated by the iodide ionic ligand is used for preparing a solar battery, the device performance which is comparable to solution phase ligand exchange can be achieved.