Abstract: The rotary arm is the key component of geotechnical centrifuge to support loads. The centrifugal acceleration of the assembly rotary arm is limited. The high acceleration design of the rotary arm can be realized by using the whole forging process and carrying loads. According to its structural characteristics, the integral rotary arm is divided into the main arm section and the pocket section. The main arm section is designed with variable cross-section and equal strength. For the pocket section, the lightweight design of the fillet at the pocket root and the pocket beam is compared respectively. The finite element analysis method is used to analyze the design results. The results show that the maximum stress of the rotary arm is less than 450 MPa and the safety factor is greater than 2 at 1700.4g. The acceleration of rotary arm exceeds the level of the existing centrifuge, which is of reference significance for practical engineering.