The　response　signals　of　Schlieren　effect　of　carbon　tetrachloride,　glucose,　sodium　chloride　and　hydrochloric　acid　in　flow　injection　systems　have　been　used　to　investigate　the　diffusion　effect　on　solution　dispersion　behavior　i.　e.　on　the　shape　of　response　curve,　travel　time,　residence　time　and　baseline-to-baseline　peak　width.　The　experimental　results　have　been　proved　to　be　in　accordance　with　the　FIA　theory.