Volatile Organic Compounds (VOCs) are widely present in our daily environment. Due to its larger tunable space and better structural properties, ZnO has been widely used in the field of optical and electrical sensing in recent years, especially in the field of gas-sensitive sensing, which has excellent research prospects. In this work, ZnO arrays were prepared and their gas-sensitive sensing performance for formaldehyde gas was systematically investigated. It is found that the ZnO array gas sensing element has better sensing performance compared with the reference sample, and the increase of hole size contributes to the improvement of sensitivity. The lower detection limit of the optimal gas sensing element for formaldehyde gas can reach 10 ppb, which is much lower than the national requirement (60 ppb). The detection performance of the ZnO array for VOC acetone was also measured.