Haohe River is a pearl embedded in Nantong City. Is it a metaphor?

Yes. In this sentence, the Hao River is compared to a pearl, expressing the importance and value of the Hao River to Nantong City. It expresses the importance of Hao River in Nantong City and also highlights the urban characteristics and charm of Nantong City. This rhetorical technique is often used in literature and language expression, which can enhance the effect and image of expression, allowing people to more deeply understand and feel the meaning to be expressed.