The invention discloses a vertical honeycomb sandwich plate, a preparation method and a sandwich plate connecting method. The vertical honeycomb sandwich plate comprises an upper face plate, a lower face plate, an upper glue layer, a lower glue layer, a honeycomb layer arranged between the upper glue layer and the lower glue layer as well as a plurality of upright columns connected with the upperface plate and the lower face plate respectively, wherein honeycomb holes of the honeycomb layer are vertical to the face plates. During preparation, a honeycomb core is arranged in a sleeving mannerafter one ends of the plurality of upright columns are fixedly connected with the lower face plate, the upper face plate is connected and fixed with the other ends of the upright columns, the upper glue layer and the lower glue layer are poured respectively, and the honeycomb sandwich plate is prepared. According to the sandwich plate connecting method, sandwich plates can be connected by arranging overlap edges or adopting solid square tubes. The honeycomb sandwich plate is low in density, light in weight and high in specific strength, specific stiffness, bearing capacity, vibration damping,sound insulation and heat insulation, and bonding strength between the core and the face plates is high; meanwhile, the method is simple, the operability is high, and the cost is low; besides, the connecting strength of the sandwich plates is high.