Recently, the large-number extended GCD algorithm is used in the core function of the next-generation blockchain systems and served as the most time-consuming operation. Considering the efficiency, speeding up this operation is urgently desired. However, the extended GCD, which is rarely explored in literature, is extremely hard to parallelize because of long serial operations with strong data dependency. In this paper, we propose a low-latency architecture for the extended GCD of large numbers by utilizing many algorithmic transformations and architectural optimizations. The experimental results for the 1024-bit extended GCD show that our design significantly outperforms the prior arts.