A novel colorimetric probe (L) was prepared and its metal ion sensing properties were investigated. Probe L exhibited obvious colorimetric response toward Hg2+ in water. The association constant for probe L-Hg2+ in water containing 0.5% DMSO (v/v) was determined as 1.77×105M−1. The detection limit of probe L for the analysis of Hg2+ was determined as 21.72ppb. Moreover, probe L can be used for selective sensing of Hg2+ based on the obvious color changes in real samples. Further, the interaction between the probe L and Hg2+ was investigated by 1H NMR titration and the probable structure of probe L-Hg2+ complex was predicted by B3LYP method.