The invention provides a horizontal evaporative concentration system, comprising an evaporative concentration unit, a gas-liquid separator, wherein, the evaporative concentration unit comprises a water supply pipe, a drug supply pipe, a horizontal rotating barrel, a cooling bin, a separating bin, a spiral delivery part, a driving part which drives the horizontal rotating barrel to rotate, and a heating part which heats the horizontal rotating barrel. The water supply pipe and the drug supply pipe respectively supply raw water and medicaments to the horizontal rotating barrel, the cooling bin is connected with the horizontal rotating barrel and the separating bin and arranged between the horizontal rotating barrel and the separating bin, the spiral delivery part passes through the horizontal rotating barrel and extends to the separating bin, and the separating bin is communicated with the gas-liquid separator. The invention has the advantage of simple structure. According to the invention, raw water can rapidly and continuously make steam and crystallized products, the steam and crystallized products can be separated completely in the separating bin; the whole process has no need of extra pipelines, the phenomenon of pipe blockage is avoided, and even the pipe blockage occurs, the blockage position is easy to be found; in addition, no problem of pipe returning evaporation exists, and the problem of pollution caused by returning evaporation is avoided.