Hydrothermal method is a unique method to deposit PZT thin film using chemical reaction between titanium substrate and solution.For its application devices, we fabricated a micro ultrasonic motor, a tactile sensor and an earphone for hearing aid.The micro ultrasonic motor was 1.4mm in diameter and revolution speed was 600rpm.The resolution of the tactile sensor was 66nm.This sensor had possibility for being used in the liquid.The earphone for hearing aid generated 60dB sound pressure with 1.3Vrpm.Now we are trying to improve these performances by investigating reaction conditions of hydrothermal method.