This paper presents the design of the SY300(kA) plus pre-baking anode reduction cell as well as the power supply commutation system. In order to design the large scale pre-baking anode tank, in addition to the software package for engineering design, a mathematical model was developed to simulate the physical field of the tank. Up to now, seven SY300kA and one SY350kA reduction cells have been designed , among which three SY300kA tanks have been commissioned with very good operating performances.