The demand of activated carbon is huge and increases exponentially, due to its extensive use in petrochemical, electric power, chemistry engineering, clinical medical treatment, environmental protection, and so on. Researches have shown that, comparing with traditional methods, the microwave-assisted produced activated carbons have more well-developed pores, larger specific surface area and more uniform porous structures. These researches, however, are confined to the laboratory level. The existed microwave heating devices have the ubiquitous problems like hot spot, thermal runaway and low heating efficiency, which impede the large-scale application of microwave energy in the activated carbon industry. In view of these problems, this paper, based on the domestic bamboo, proposed a design of microwave uniformly heating apparatus for bamboo based activated carbon production. With multi-physics calculation and the evaluation standards of heating uniformity of materials and the energy feed rate, the device parameters are optimized and a heating equipment is obtained with S11 of -26.81dB and temperature variation coefficient of 0.2834. Besides, this paper also verifies the robustness and accuracy of this simulation model with sweeping parameters and applying different numerical simulation methods. This work may present guiding significance for the design of large-scale microwave heating devices in the activated carbon industry.