Legal analysis: the main evidence that the defendant should provide in patent infringement cases: 1. Preserve the alleged infringing products; 2. Investigate the financial books of the alleged infringing unit to determine the amount of compensation; 3. Obtain the evidence of the alleged infringer's infringement; 4. Evidence about the infringer; 5. Evidence of infringement facts; 6. Evidence about damages.
Legal basis: Article 67 of the Patent Law of People's Republic of China (PRC). In a patent infringement dispute, if the accused infringer has evidence to prove that the technology or design he implemented belongs to the existing technology or design, it does not constitute patent infringement.