Exploring the replication of hybridization chain reaction HCR ( r HCR) for reciprocal amplification is intriguing in biosensing and bioanalysis. Herein, we develop a r HCR-based fluorescence platform that is manipulated by the combination of a specific DNA trigger ( T ) and a T -analogous amplicon ( T* ), thereby concatenating multi green-emissive Ag nanoclusters ( mg AgNCs) for amplifiable signal readout. Four well-designed hairpins (H1 recognizing T , H2, H3, and H4) with sequential complements are executed to operate r HCR. The termini of H1/H3 are merged to hybridize an inhibiting strand ( I ). The parent scaffold for mg AgNCs is separated into two splits (C 4 AC 4 T and C 3 GT 4 ) that are individually overhung in H2/H4. The presence of T activates the first HCR amplifier through cross-hybridization of four reactive hairpins for forming HCR duplexes. The next invasion of a complex ( T * ·I ) drives I to hybridize the tandem repeats in H1/H3, so that the displaced T* functions as T to catalyze the second amplifier r HCR for feeding back more hairpin assemblies with rapid reaction kinetics. In the shared r HCR polymers, the parent scaffolds (C 4 AC 4 TC 3 GT 4 ) in H2/H4 are collectively concatenated for the preferential clustering of mg AgNCs adducts, which cooperatively emit enormous T -responsive fluorescence signal. Because of the localization of T in HCR products, an alternative amplicon T* is introduced to drive r HCR progress via DNA strand displacement, generating more nucleating sites of emitters. Thus, the rational combination of nonenzymatic r HCR and label-free fluorescent concatemers would create a reciprocal signal amplification, achieving a simplified, rapid, and highly sensitive assay down to femtomolar concentrations.