This research investigates the mechanical property of the concrete which were mixed with chemical admixtures and treated by magnetic field. Two chemical admixtures were used in this research: Concrete superplasiticizer SW-4 and early strength admixtures CF. Magnetic treated admixtures were obtained by passing liquors through a concrete magnetic-field-generating machine. Test variables included admixture dosage and curing age. Results show that liquor’s conductivity and surface tension have some special changes after treated by magnetic field, and using magnetic treated admixtures could improve the compressive strength of the concrete, reduce the setting times and improve its fluidity and magnetization improved cement hydrate degrees.