The invention belongs to the technical field of gas treatment, and relates to a vertical multi-bed regenerative thermal oxidizer (RTO) bell-shaped temperature area gradient symmetry control method. The control method of a whole system controller includes two stages, namely, determining the reversing time and determining the working state of the RTO, the reversing time and phi 1, phi 2 and phi 3 opening values are transmitted to an RTO controller, when a system operates in a stable state, the revering time (half cycle) is determined by a t value obtained by a feedforward control algorithm, then the system operates, dynamic online regulation is carried out according to the change situation of the average temperature T of a combustion chamber so as to ensure that the RTO operatesin a safe and stable state, and the system is enabled to have higher heat energy recovery efficiency and higher oxidation rate of gas (methane).