Is it illegal to sell high imitation but tell the other party that it is high imitation?

Illegal. According to Baidu's legal information query, selling high-quality imitations is an act of producing and selling fake and shoddy products. It is a voluntary business activity to inform the other party of high imitation goods, but it is illegal to sell high imitation goods by yourself, so it is still illegal to inform the other party of high imitation goods.