A novel thin film micro sensor sensitive to cadmium (II) ion was made by depositing the cadmium ion selective chalcogenide glasses (Cd-Ag-As-I-S) materials on the surface of a light-addressable poten-tiometric sensor (LAPS) using pulse laser deposition (PLD) technique. The substrate of the sensor is a single crystal silicon of N type and the metal contact layers are Cr/Au. The detection limit of the thin film sensor was tested to be 1.15 × 10^-7 mol/L, the response time less than 2 min, and the application scope of pH from 4 to 7. The sensor has good inhibition ability to interfering ions. The thin film sensor has the characteristics such as rapid detection, few sample solutions and low detection limit. Contrasted with a ion-selective electrode (ISE), the sensor improves the sensitivity for its response signal is alternating-current excited by an alternating light. The results show that PLD technique is a new and effective method for preparing thin film micro integrating sensors.