In this work, the influence parameters, including synthesis temperature, nitrogen pressure, and isothermal dwell time, were systematically investigated during carbothermal preparation of zeta-Cr-2(C,N) solid solution powders by using thermogravimetry differential scanning calorimetry, X-ray diffraction, scanning electron microscope, and composition analysis. The results showed that Cr2O3 began to be carbonized at 1000 degrees C firstly and then was nitrided with the formation of Cr-2(C,N) at elevated temperature, and finally zeta-phase Cr-2(C,N) particles were obtained at the optimal condition of 1200 degrees C for 1 h under the N-2 pressure of 0.02 MPa, which showed lowest oxygen (0.82 wt%) and highest nitrogen (6.25 wt%) content with the diameter of similar to 3 mu m. Increasing temperature, N-2 pressure, and dwell time facilitates the reduction of oxygen. However, these parameters must be carefully controlled under reasonable ranges to preventing quality deterioration. In addition, the crystal structure of zeta-Cr-2(C,N) was characterized by transmission electron microscope and neutron powder diffraction (NPD). Based on the selected area diffraction and NPD patterns, the crystal structure of Cr-2(C,N), prepared in this work, was confirmed to be orthorhombic (Pbcn) as well as the interstitial atoms (C and N) were zeta-type occupational ordering.