This paper presents the development and experimental process of our system for the Formosa Speech Recognition Challenge 2025 (Hakka ASR). The proposed system is built upon the OpenAI Whisper model. We achieved significant performance improvements for the Sixian dialect of Hakka through dataset preprocessing and model fine-tuning. In the warm-up evaluation, our system achieved a Character Error Rate (CER) of 10.51% on the character recognition track and a Syllable Error Rate (SER) of 14.72% on the pinyin recognition track. In the final evaluation, our system achieved a Character Error Rate (CER) of 11.21% on the character recognition track and a Syllable Error Rate (SER) of 15.08% on the pinyin recognition track.