Observe the handwriting, distinguish weight and size, and seek professional appraisal.

1. Observe the handwriting: Genuine Qianlong Tongbao handwriting is generally clear, regular, and smooth lines, while counterfeit handwriting is blurry, rough, and irregular.

2. Distinguish the weight and size: The weight and size of the normal Qianlong Tongbao will meet the standards. If there is an obvious deviation, it is a counterfeit coin.

3. Seek professional appraisal: If you have any doubts about the authenticity of Qianlong Tongbao, you can consult a professional antique collection institution or appraisal expert to conduct appraisal through professional methods and equipment.