He wrote a calligraphy work, the content of which is "Huanxi Sand" by Nalan Xingde. Is it appropriate to give it to old classmates?

Whether it is appropriate or not depends on how you feel about that old classmate and how you want her (him) to react when she receives your gift. Of course, in fact, you don't have to care about this. After all, the gift is just an expression of your mind, as long as this work, the word is the other person's favorite.