Polymorphisms within microRNAs can lead to phenotypic variations in organisms. The purpose of this research was to investigate the potential impact of the pre-miR-1687 single nucleotide polymorphism (SNP) on the economic characteristics of weight and body size in chickens. The SNP was genotyped using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. A linear mixed model was utilized to analyse the associations between the SNP and chicken body size and growth traits. The SNP in the pre-miR-1687 gene was correlated with F2 chicken body weight (BW) at birth and at 4, 6, 8, and 10 weeks of age. The SNP in the gga-miR-1687 gene was correlated with shank length, shank girth, pectoral angle (at 4 weeks), and pelvic breadth (at 8 weeks). Different BW genotypes were observed in the studied flocks. The changes in the secondary structure of pre-miR-1687 and in the free energy values were estimated using online M-fold software. The results serve as a helpful resource for subsequent research on the mechanisms and functions of miRNAs. In addition, the study provides a credible basis for the application of biomolecular technology in poultry breeding.