The　study　on　transport　regularity　of　contamination　can　provide　theoretical　evidence　for　forecasting　the　potential　hazard　of　contamination　to　underground　water　environment　and　safety　disposal.　In　this　paper　analytic　solution　of　transport　model　on　ammonia　nitrogen　in　soil　under　the　condition　of　unchangeable　contamination　concentration.　According　to　model　solution　transport　situation　of　contaminant　on　different　kinds　of　soil　which　are　clay,　heave　silt　clay,　silt　clay　and　clay　silt　has　been　simulated.　The　results　have　shown　that　the　obstruct　performance　to　contaminant　of　clay　is　the　best　and　the　obstruct　performance　to　contaminant　of　clay　silt　is　the　worse.