The adsorption properties of formaldehyde on the Cr and Cu doped ZnO surface were investigated by using the density functional theory (DFT). The results showed that the binding capacity of the ZnO sensor material to formaldehyde was improved by doping with Cr atoms. Meanwhile, doping Cu atoms showed no obvious enhancement on the formaldehyde binding capacity. The binding distance of formaldehyde to the Cr and Cu-doped ZnO was calculated to be 1.937 and 2.031 A, respectively, with the binding energy of 0.775 and 0.376 eV. After doping, the width of the conduction band increased and impurity levels appeared. The adsorption process of formaldehyde on the Cr and Cu doped ZnO surface belongs to physical adsorption. It is expected that the calculated results reported in the present study can provide worthwhile references for the theoretical investigations and future design of ZnO material for enhancing its performance by doping with different elements.