Urea ammonium nitrate solution (UA) is a kind of aqueous solution of urea and ammonium nitrate. Because the mixture of urea and ammonium nitrate has very low critical relative humidity (18% at 30 ° C), liquid can only be used as fertilizer at room temperature. Compared with the traditional nitrogen fertilizer, the UA has better energy saving effect. The solid fertilizer now is actually evaporated from the fertilizer plant, evaporated and then granulated, and then transported to the farmer. The farmer then applied it back to the ground, which is more energy consuming. The UA products remove the process of concentration and crystallization, and the original fertilizer produced can be concentrated slightly to the required concentration. In this way, unnecessary production links are removed, and the better energy saving effect is achieved, and the cost is also greatly reduced. Urea ammonium nitrate solution is a kind of nitrogen fertilizer mixed with urea and ammonium nitrate, in which nitrogen elements come from three forms of nitrogen: nitrate, ammonia and amide. The multiple nitrogen makes the nutrient more effective and lasting.