The invention relates to an ammonia storage mixed porous solid sample block containing expansion graphite, which is prepared by mixing anhydrous strontium chloride, the expansion graphite and industrial ball clay. The invention is characterized in that the preparation method of the mixed porous solid sample block comprises the following steps: 50 to 82 percent by weight of the industrial powdered anhydrous strontium chloride, 2 to 10 percent by weight of the expansion graphite, 3 to 16 percent by weight of the industrial ball clay, 4 to 18 percent by weight of deionized water and 4 to 14 percent by weight of industrial alcohol are mixed, and are uniformly stirred by a stirrer for 1 to 10 h to form semidry mixed powder; the powder is added into an openable closed vessel to be subjected to mechanical oscillation for 30 to 60 min; and then the powder is dried for 1 to 2 h under the circumstances that the temperature is 80 to 120 DEG C and the degree of vacuum is 1 to 10<-1> KPa, or is dried for 2 to 4 h at the temperature of 60 to 100 DEG C. The prepared mixed porous solid sample block has the advantages of super-strong adsorbability, stable structure and low possibility of pulverization; and as a defined amount of industrial ball clay, which has excellent physical adsorptivity and surface chemical activity, is added into the mixed porous solid sample block, the viscosity and the adsorbability of the dried mixed porous solid sample block are further improved.