Abstract: Because there are many disadvantages in traditional humidity generators, based on summarizing and absorbing the research achievements of humidity generator, and relative humidity of the air which in equilibrium state with saturated salt solution is just the function of temperature, the authors researched and developed a humidity generator which could generate gas with continuous value of humidity. In this development, microcomputer control system was used to automatically control the temperature. The research and development of this type of humidity generator filled the equipment gap in China. Therefore, the humidity generator has significant values of research and practicality.