PHREEQC is a computer software (Parkhurst and appelo, 1999) for the calculation of various low-temperature hydrogeochemical reactions. PHREEQC, based on the ion linked water model, can (1) calculate the species and saturation index of matter formation; (2) simulate geochemical inversion process; (3) calculate batch reaction and one-dimensional migration reaction. In addition, PHREEQC coupled with multi-component solute transport model can generate PHAST, a three-dimensional reaction transport simulator for simulating groundwater flow system. PHREEQC is also useful in the investigation of unpolluted and polluted environment, laboratory, field and regional investigation. PHREEQC can investigate various natural and human influenced environmental geochemical reactions, including acid mine water discharge, radioactive waste isolation, pollutant migration, nutrient enrichment, aquifer natural and artificial restoration, aquifer reserve recovery, drinking water treatment, indoor experiment and regional aquifer system. PHREEQC has two graphical user interfaces available. Phreeqcl is a screen driven interface that provides a descriptive explanation for each data item (Charlton and Parkhurst, 2002). PHREEQC used in windows is a row editing object interface. Its additional input features enable it to generate graphic simulation results (post, 2004).