The invention particularly provides a high-performance 
humidity sensor which comprises n-n homotype 
heterojunction materials formed by a stannic 
oxide thin film and a 
silicon substrate covered with a 
silicon-dioxide layer and takes 
palladium as a catalytic layer. A preparation method of the resistance-type 
humidity sensor comprises the steps that the stannic 
oxide thin film is grown on the 
silicon substrate covered with 
silicon dioxide through a 
sputtering method firstly; then the 
palladium catalytic layer with the area smaller than the stannic 
oxide film is prepared on the surface of the thin film through a 
mask film and the 
sputtering method. According to the resistance-type 
humidity sensor based on the Pd / SnO2 / Si 
heterojunction and the preparation method thereof, the Pd / SnO2 / Si 
heterojunction humidity sensor is prepared by means of the 
catalytic effect of the 
palladium film and the amplification effect of the stannic oxide-
silicon heterojunction, the technology is simple, the cost is low, a heater is not needed, the humidity sensor can work at the 
room temperature, the humidity sensor has the advantages of being low in 
energy consumption, high in sensitivity and short in response and 
recovery time, the good detection property to 
water vapor is achieved, and important application prospect is achieved.