The requirements of couplets are as follows: a couplet consists of upper couplet and lower couplet. The number of words of the upper and lower conjunctions should be equal, the parts of speech of the upper and lower conjunctions should be the same, and the positions of nouns, verbs, adjectives and adverbs should correspond. The upper and lower tones should be in tune, read harmoniously, strewn at random and ups and downs, and be pleasant to listen to. The content of the upper and lower couplets should be continuous and inherited to express a complete artistic conception. The combination of couplets and calligraphy forms a unique China culture.