Three structurally simple thiourea derivatives 1–3 were prepared, and their chromogenic behaviors toward various anions were investigated in aqueous solution. Among them 1 showed good sensitivity and selectivity for cyanide ion and also can distinguish it from other anions by different color changes. Besides that, the receptor 1 has a sensitive detection limit (1.27 μM) for cyanide ion accordingly it can be used as a colorimetric sensor for the determination of cyanide ion. The use of the test strip of sensor 1 to detect cyanide ion was also reported.