Abstract: The soil column test in laboratory were used to investigate nitrogen transpor and transformation.A new type of tension sensors was used to collect soil-tension data automatically.Through tests of the soil column,enough data were obtained.This paper estimated the soil hydraulic,transport and transformation parameter by using tracer and a combined simulation-optimization approach under variably flow condition.A nonlinear weighted least square algorithm was used to estimate the model parameters by minimizing deviations and those predicted by the numerical model transpor and transformation process.