Cxtfit is a computer software developed by the saline soil laboratory of the United States to study one-dimensional soil solute transport. Based on Levenberg Marquardt algorithm, cxtfit uses the function optimization method of nonlinear least square to fit the breakthrough curve of solute mixture replacement experiment, solves the model parameters, and predicts the concentration distribution of solute in soil with time and space. Cxtfit is based on the solute convection dispersion equation. The original cxtfit1.0 was developed and compiled by Parker and van Genuchten, and gradually improved into today's cxtfit2.0, which contains more equation analysis for different initial boundary value problems and generation problems. The software includes three different types of solute transport models: equilibrium CDE model, physicochemical nonequilibrium CDE model and stochastic flow tube model.