A reactor configuration comprises an inlet section I, a preheating section II, a transition section III, a reaction section IV and an outlet section V; except for the preheating section II and the reaction section IV, the existence of the inlet section I, the transition section III and the outlet section V depends on reaction conditions; and the process realizes no coke deposition synthesis of methane and high selectivity synthesis of ethylene. The methane conversion rate is 20-90%; ethylene selectivity is 65-95%; propylene and butylene selectivity is 5-25%; aromatic hydrocarbon selectivity is 0-30%; and coke deposition is zero.