Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO 3 ) 3 ·6H 2 O affords three isostructural Ln-complexes Eu(L) 3 (H 2 O) 2 n ( 1-Ln ) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-Tb x Eu 1− x coordination polymers were also obtained by mixing different ratios of Eu 3+ and Tb 3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10 −4 M) for the simultaneous sensing of MnO 4 − , CrO 4 2− and Cr 2 O 7 2− ions in water. Three synthesized Ln-CPs show tunable emission colors through bimetallic doping and sensing for MnO 4 − , CrO 4 2− and Cr 2 O 7 2− ions in water.