The invention discloses a treatment method for slaughter wastewater. The treatment method includes the steps of pretreatment, biochemical treatment, precipitation separation, oxidative decolorization, activated carbon adsorption, disinfection treatment and sludge concentration. Through adopting the advanced, practical, mature and reliable treatment technology, the inflow requirements for water large in water quality fluctuation and amount are met, and it is ensured that the treated wastewater can not be discharged until reaching standards. By the adoption of the reasonable technology and reasonable arrangement, the construction cost is lowered as far as possible, and on the premise of guaranteeing safe, economical and stable operation of a system, the good treatment effect is achieved with the minimum investment. Based on the rule of the advanced and mature technology and reliable quality, the relation between manual operation and automatic control is reasonably handled, an automation technology is adopted for the step where manual operation is inconvenient, and the labor cost is high, and therefore the operation management level of the system is increased.