The invention relates to a carbon-sand filter tank. The carbon-sand filter tank comprises a left tank body, a right tank body, a water inlet channel, a filter board, a supporting board, a quartz sand layer, an activated carbon layer, a water outlet channel and a roof; the left tank body and the right tank body are arranged side by side, and are communicated; anti-corrosive coatings are arranged on inner walls of the left tank body and the right tank body; a plurality of water distribution slots are formed in the upper parts in the left tank body and the right tank body; the water distribution slots are connected with the water inlet channel for discharging water into the left tank body and the right tank body; the filter board, the supporting board, the quartz sand layer and the activated carbon layer are sequentially arranged on the bottom of the left tank body from bottom to top; aeration holes are formed in the right tank body; the water outlet channel is enclosed at the outer sides of the left tank body and the right tank body, and a water outlet flashboard is arranged among the water outlet channel, the left tank body and the right tank body; and the roof is erected on the tops of the left tank body and the right tank body by a plurality of framework columns. The carbon-sand filter tank disclosed by the invention has the advantages such as a simple structure, good ammonia nitrogen removal effect, high removal speed, low treatment cost and the like.