Number Theoretical Transform (NTT) hardware accelerator becomes crucial building block in many cryptosystems like post-quantum cryptography. In this paper, we provide new insights into the construction of conflict-free memory mapping scheme (CFMMS) for multi-bank NTT architecture. Firstly, we offer parallel loop structure of arbitrary-radix NTT and propose two point-fetching modes. Afterwards, we transform the conflict-free mapping problem into conflict graph and develop novel heuristic to explore the design space of CFMMS, which turns out more efficient access scheme than classic works. To further verify the methodology, we design high-performance NTT/INTT kernels for Dilithium, whose area-time efficiency significantly outperforms state-of-the-art works on the similar FPGA platform.