The long-span continuous beam bridge with parallel twin steel box decks is common in engineering practice，but the complex vortex shedding and interaction of parallel twin steel box girders may cause significant vortex-induced vibration （VIV），affecting the fatigue performance of the structure，driving comfort，and possibly causing social panic. This paper takes parallel twin box girders as the research background，and a large-scale segment model vibration and pressure measurement wind tunnel test is carried out. The evolution characteristics of the distributed aerodynamic force in the entire vertical bending vortex vibration process （before the vortex vibration，the ascending zone，the amplitude extreme point，the descending zone，and the end of the vortex vibration） under different spacings are compared，and effective aerodynamic measures to control the vortex vibration of the parallel twin box girders are proposed. The study shows that the vortex-induced vibration lock-in regime of the parallel twin steel box girders is long，the amplitude is large，+3° is the most unfavorable angle of attack （AOA） and the frequency multiplication effect of the vortex excitation force is related to the amplitude and the spacing between the box girders. When the spacing makes the inter-slot vortex fully developed，it significantly increases the pulsation of the aerodynamic force distributed near the slot. In the case of small spacing and low wind speed，the distributed aerodynamic force on the lee side of the upstream and downstream girders enhances the vortex-induced vibration. At large or small spacing with high wind speed，the distributed aerodynamic force on the upper surface near the slot and the position of the inclined web of the downstream girder plays a major role in enhancing the vortex-induced force，which is the inducement of the large amplitude of vortex-induced vibration of the parallel twin box girders. A comprehensive aerodynamic control measure of setting the apron between the slots and setting the wind fairing at both ends is proposed，which can cut off the propagation path of the vortex between the slots and reduce the contribution of the distributed aerodynamic force at the bridge deck. The measure can effectively reduce the vertical bending vortex-induced vibration of the parallel twin steel box girders.