Traditional industrial methanation of coke oven gas (COG) to produce natural gas generally requires three or more adiabatic reactors, thus resulting in a long process flow, rapid deactivation of catalyst and high investment cost. Herein, a new methanation process of COG (denoted as NCtSNG) over the Ni-Ce/γ-Al2O3 catalyst was proposed, wherein a tubular heat exchange reactor and an adiabatic reactor were connected in series. The pilot-scale methanation test using a single tubular heat exchange reactor was performed, and the result demonstrated that heat exchange reactor would insure a low temperature of catalyst layer (below 500 °C), which can not only improve the efficiency of the exothermic methanation but also prolong the catalyst lifetime. A reliable simulation of the NCtSNG process was then established and validated by using the commercial software Aspen Plus based on the pilot test, and the key operation parameters and conditions were optimized so as to provide significant basic data for future industrial production. It was estimated that the new NCtSNG process presents high energy efficiency of 80%, low production cost of 2.15 CNY/m3-SNG, and low CO2 emission of 0.61 kg/m3-SNG, thus showing a great superiority in market competition.