The present invention relates to a chiral spiro phosphine-nitrogen-sulfur (P—N—S) tridentate ligand, preparation method and application thereof. The P—N—S tridentate ligand is a compound represented by Formula I or Formula II, their racemates, optical isomers, or catalytically acceptable salts thereof. The ligand has a primary structure skeleton characterized as a chiral spiro indan skeleton structure with a thio group. The chiral spiro phosphine-nitrogen-sulfur tridentate ligand can be synthesized by reacting racemic or optical active compound 7-diary/alkyl phosphine-7′-amino-1, 1′-spiro-dihydro-indene compound having a spiro-dihydro-indene skeleton as the starting material. The chiral spiro P—N—S tridentate ligand being complex with transition metal salt can be used in an asymmetric catalytic hydrogenation reaction for catalyzing carbonyl compound. In particular, in asymmetric hydrogenation reaction process, being complex with iridium for catalyzing β-alkyl-β-keto ester can obtain a high catalytic activity (a catalyst amount of 0.0002% mol) and high enantioselectivity (up to 99.9% ee) result. So the present invention has a practical value for industrial and commercial production.