The invention discloses a lead-free piezoelectric ceramic material with giant piezoelectric response and a preparation method thereof. The material composition is Ba0.975Sr0.005Ca0.02Ti0.87Sn0.12Cr0.01O3+0.05wt%Co+0.05wt%Cu. Specifically, Ba0.975Sr0.005Ca0.02Ti0.87Sn0.12Cr0.01O3 is prepared by solid-phase synthesis, Co and Cu are respectively formed by secondary coating in the form of precipitateon the surface, a special hierarchical subgradient structure is produced by sintering technology, and a giant piezoelectric effect is produced, the properties currently exceed all reported lead-free piezoelectric ceramics. Experimental measurement indicates that the product has excellent piezoelectric properties, the quasi-static piezoelectric constant d33=1820pC/N, piezoelectric strain constant shown as the specification is 2032pm/V, the lead-free piezoelectric ceramic material provided by the invention has the advantages of stable performance and low cost, and is suitable for large-scale industrial production.