The invention relates to a medium-sized pure electric bus chassis which comprises a chassis body, a first front wheel, a second front wheel, a first rear wheel, a second rear wheel, a front axle and a rear axle, wherein the first front wheel, the second front wheel, the first rear wheel, the second rear wheel, the front axle and the rear axle are arranged on the chassis body, the front axle is arranged between the first front wheel and the second front wheel, and the rear axle is arranged between the first rear wheel and the second rear wheel. An electric steering system, a power source system, a driving system, a control system and a brake system are arranged on the chassis body. The electric steering system is positioned in the front section of the chassis body, the power source system is positioned in the middle section of the chassis body, the driving system and the control system are positioned in the rear section of the chassis body, and the brake system is distributed on the whole chassis body in a penetrating manner. Electric energy serves as a power source, the power performance and safety of a power system can be ensured when a bus runs, and zero emission, energy conservation and environmental protection can be realized.