AVS3 is a newly proposed video coding standard by the Audio Video coding Standard Workgroup, demonstrating higher compression efficiency than the High Efficiency Video Coding standard. Advanced entropy coding is one of the performance bottlenecks of the AVS3 standard video encoder due to the strong data dependency in its arithmetic coding process. A novel arithmetic encoding hardware structure is presented in this paper, and as we know, this is the first paper on AVS3 AEC hardware implementation. Firstly, we select and apply the typical optimization schemes adopted in HEVC context-based adaptive binary arithmetic coding designs. Secondly, Utilizing the unique characteristics of AVS3 AEC, we propose mathematical reordering, variable-clock-cycle range updating and variable-clock-cycle context modeling methods to optimize the critical path. Our design can encode 2.6457 bins per clock cycle, and the corresponding throughput is 3131 Mbin/s in Globalfoundries 28nm process. Compared with the basic anchor structure, it has obtained a performance improvement of 319% and can meet the 8k@120fps ultra-high-definition video encoding requirements.