The ferromagnetic properties of Zn 0.875 Co 0.125 O and Zn 0.875 (Co 0.5 Mn 0.5 ) 0.125 O are investigated using total energy of plane wave and ultrasoft pseudopotentials method based on the density functional theory (DFT). The results show that Zn 0.875 Co 0.125 O and cobalt (Co) and manganese (Mn) codoped ZnO-based dilute magnetic semiconductors (DMSs) are of the ferromagnetic order, and the ferromagnetism mostly comes from interaction of spin-polarized oxygen atoms, zinc atoms and transition metals. Meanwhile, it is also found that the magnetic moments are mostly contributed by the spin-polarized oxygen atoms and transition metals. In addition, the electron sharing for the 3d states of transition metals (Co, Mn) and 2p states of O atoms is exacerbated as compared to pure ZnO and Co doped ZnO, helping to obtain p-type ZnO. These results indicate that Co and Mn codoped ZnO are promising magneto-electronic materials and they can be used for nanoscale spintronics device material.