In this paper, we construct a fluorescence nucleic acid probe based on DNA-templated silver nanoclusters (DNA-Ag NCs) for the detection of the p53 gene. The fluorescence biosensing of the "turn-on" model is successfully implemented as a result of the target-triggered configurational change in the hairpin DNA probe and the synthesis of fluorescent Ag NCs. With this biosensor, the limit of detection (LOD) for the p53 gene is 3.57 nM and the linear range is 250-2500 nM in phosphate buffer solution, while a LOD of 6.06 nM in the linear range of 250-2500 nM is obtained in 1% diluted fetal calf serum. So this probe, with its advantages of specificity, practical application, easy operation and low cost, will have favourable development prospects in biological sensing and imaging.