Under the background of economic globalization, British and American movies and TV series have become one of the important ways of cultural exchange and communication between China and the west, and subtitle translation also plays an increasingly important role in cross-cultural communication. Taking the American sitcom "the Big Bang Theory" as an example, its language is characterized by humor and personality. This paper first summarizes the characteristics of subtitle translation of sitcoms, then analyzes the types of humor translation from three aspects: general humor, cultural humor and linguistic humor, and then analyzes the specific examples of "addition, subtraction, compilation and modification" to investigate the guiding role of translation variation theory in subtitle translation.