As everybody knows,Mark Twain is a great social critic as well as a great humorist in the late 19th century.In order to present the characteristics of Mark Twain’s humor,the paper mainly discusses his writing techniques from different points of view.On the one hand,Mark Twain’s humor is distinguished for his liberal use of funny American vernacular style,which breaks away from the influence of British traditional literature and fully embodies the spirit of America.On the other hand.Mark Twain uses various figures of speech,such as irony,exaggeration,contract,anti-climax and repetition,etc,to probe deeply into the character and conscience of the world,to teach people lessons about society. As everybody knows, Mark Twain is a great social critic as well as a great humorist in the late 19th century. In order to present the characteristics of Mark Twain’s humor, the paper mainly discusses his writing techniques from different points of view. On the one hand, Mark Twain’s humor is distinguished for his liberal use of funny American vernacular style, which breaks away from the influence of British traditional literature and fully embodies the spirit of America. On the other hand. Mark Twain uses various figures of speech, such as irony, exaggeration, contract, anti-climax and repetition, etc, to probe deeply into the character and conscience of the world, to teach people lessons about society.