The technology adopts gravity/air flotation degreasing and other pretreatment methods to remove oil in wastewater, the ammonia in wastewater is removed and recovered by ammonia distillation tower, phenols in wastewater are removed and recovered by extraction method, and then the wastewater enters biochemical A/O treatment to reduce COD, advanced oxidation to further reduce COD, hardness removal unit to reduce the hardness of wastewater, ultrafiltration, sodium filtration, produced water reuse, concentrated water enters multi-effect evaporation and concentration, and then enters centrifuge for dehydration to obtain solid salt.