Amorphous indium zinc oxide (a-IZO) thin film transistors (TFTs) with different channel layer thickness were fabricated on silicon wafers by radio frequency magnetron sputtering method at room temperature. The influence of channel layer thickness on initial electrical characteristics and aging effect of a-IZO-TFTs were investigated. At the same time, the positive / negative bias stress stability of initial and 60-days-aged a-IZO-TFTs were compared. All results indicate that thin channel layer a-IZO-TFTs exhibit good anti-aging effect and bias stability.