The invention relates to MOFs (Metal-Organic Frameworks) with ph stability. The chemical formula of the MOFs is {[Zn2.5(nbta)(trz)2(H2O)].3H2O}n, wherein the nbta is 5-nitro-1,2,3-benzene tricarboxylic acid radical ions, and trz is 1H-1,2,4-triazole; the preparation method comprises the following steps: adding zinc nitrate, the 5-nitro-1,2,3-benzene tricarboxylic acid radical ions and the 1H-1,2,4-triazole into a water solution, using anhydrous sodium carbonate to regulate the PH value, reacting for 72 h at the temperature of 80 DEG C, conducting filtration and washing, and obtaining the target product; the MOFs can be used for selective adsorption separation of the CO2/N2. The MOFs have the advantages that the preparation technology of the MOFs is simple, the operation is easy, the cost is low, the period is short, the productivity is high, the prepared MOFs have better ph stability and further have better selective adsorption separation performance on the CO2/N2.