A field-level model that used to simulate fate and transport of herbicides (PCPF-1) was integrated into a basin-scale model simulating water and pollutant transport called Soil and Water Assessment Tools (SWAT), to create a new model namely PCPF-1WAT. The PCPF-1WAT model was used to simulate the herbicide mefenacet (MF) fate and transport in Sakura river basin (Ibaraki Prefecture, Japan) with the use of measurement results of mefenacet concentrations throughout a rice crop season in 2008. The modeling setups for simulating the fate and transport of rice herbicides was implemented by providing model parameters related to meteorology, hydrology, land use, herbicide and management measures. The aim of this study is to simulate the fate and transport of four herbicides namely Mefenacet (MF), Bensulfuron-Methyl (BSM), Imazosulfuron (IMS) and Pretilachlor (PTC) applied to rice paddy fields in the Sakura river basin, Japan using the PCPF-1WAT model. Then, analyze the potentials for applying the model to the actual conditions of Vietnam.