Existentialism appeared in the twenties of the 20th century and became widespread in the sixties. The representatives of this school are German philosopher Heidegger and French Sean-Paul Sartre and Camus. The existentialists invariably pay their attention to man’s living condition and show their ultimate concern about man’s existential value. They hold that man’s living experiences in the world are absurd and alienated,advocating man’s free will,choice and individual responsibility. In A Farewell to Arms Through Henry’s tragic fate,Hemingway exhibits people’s unfortunate fate ruined by the devilish war,accuses the war’s brutality and absurdity,condemns the war’s destructive consequences brought to the entire human being and also investigates causes of the formation of “the lost generation” This thesis attempts to analyze man’s dilemma and his cognition of the outside world from the perspective of existentialism,revealing Hemingway’s unique understanding of man’s living condition and existential meaning in the world. Existentialism appeared in the twenties of the 20th century and became widespread in the sixties. The representatives of this school are German philosopher Heidegger and French Sean-Paul Sartre and Camus. The existentialists invariably pay their attention to man’s living condition and show their ultimate concern about They hold that man’s living experiences in the world are absurd and alienated, advocating man’s free will, choice and individual responsibility. In A Farewell to Arms Through Henry’s tragic fate, Hemingway attractions people’s unfortunate fate ruined by the devilish war, accuses the war’s brutality and absurdity, condemns the war’s destructive consequences brought to the entire human being and also investigates causes of the formation of “the lost generation ” This thesis explores man’s dilemma and his cognition of the outside world from the perspective of existentialism, revealing Hemingway’s unique understanding of man’s living condition and existential meaning in the world.