Abstract: Nano-CdIn₂O₄ powders were prepared by chemical coprecipitation and solid state reaction method. The effects of preparation condition on the phase constituents of material were investigated. The results demonstrated that nano-CdIn₂O₄ can be obtained under the condition that at pH=7~8, the starting molar ratio Cd/In is 1.3/2 and the sintering temperature is higher than 500 ℃. The size of grain sintered at 800 ℃ for 4h is only 26nm and the grain growth activiation is about 26.8kJ/mol. The conductivity of CdIn₂O₄ was studied, the results revealed that the conductance of CdIn₂O₄ was influenced by atmosphere. The carrier is electron ionized from oxygen vacancies. In air, it was affected by the amount and state of absorbed oxygen on the surface of CdIn₂O₄ powder. While increasing temperature, the conductance of CdIn₂O₄ based sensor increases with increasing temperature from room temperature to 150 ℃and decrease with increasing temperature from 150 to 500 ℃. But in Ar, it exhibits somewhat metal conductivity, because the electron concentration is high and the mobility of electron decrease with increasing temperature. The investigation of CdIn₂O₄ gas-sensing properties demonstrated that CdIn₂O₄ based sensors have higher sensitivity and good selectivity to acetone.