The invention provides a modular drying oven structure. A shell is internally provided with a heat insulation layer. The front side and the rear side of the shell are provided with drying oven doors.A tunnel air inlet chamber is arranged on one side of an inner cavity of the shell, and a tunnel return air chamber is arranged on the other side of the inner cavity of the shell. A tunnel drying chamber used for drying materials is arranged between the tunnel air inlet chamber and the tunnel return air chamber. A draught fan air inlet chamber is arranged above the tunnel drying chamber. A heateris arranged in the draught fan air inlet chamber. A draught fan air outlet chamber is arranged above the draught fan air inlet chamber. A circulating fan is arranged on a partition board between the draught fan air inlet chamber and the draught fan air outlet chamber. The circulating fan is embedded in the inner cavity of the shell from the top of a drying oven. The upper end of the tunnel air inlet chamber communicates with the draught fan air outlet chamber. The upper end of the tunnel return air chamber communicates with the draught fan air inlet chamber through a circulating air filter. Temperature sensors are arranged in the draught fan air inlet chamber or the draught fan air outlet chamber or the tunnel drying chamber. The output ends of the temperature sensors are connected with control devices. The output ends of the control devices are connected with the control signal input end of the heater and the control signal input end of the circulating fan.