The invention relates to a
cracking auxiliary agent for increasing low-carbon olefin concentration. The
cracking auxiliary agent contains a modified beta
molecular sieve, a first clay-containing
phosphorus-aluminum inorganic binder, and other inorganic binders and VIII group
metal additives, and contains or does not contain second clay, wherein the first clay-containing
phosphorus-aluminum inorganic binder comprises an aluminum component, a
phosphorus component and first clay, the modified beta
molecular sieve containing the phosphorus and the
transition metal comprises 1-10 wt% (calculated as P2O5) of the phosphorus and 0.5-10 wt% (calculated as
metal oxide) of the
metal, and in the 27Al MAS NMR of the
molecular sieve, a ratio of the
resonance signal peak area at the
chemical shift of 40+ / -3 ppm to the
resonance signal peak area at the
chemical shift of 54+ / -3 ppm is more than or equal to 1, and the sum of the
resonance signal peak areas at the chemical shifts of 0+ / -3 ppm and -12+ / -3 ppm accounts for less than or equal to 10% of the total
peak area. According to the present invention, the
cracking catalyst composition is used for catalytic cracking of
petroleum hydrocarbons, and can be provided for increasing the catalytic cracking liquefied gas yield, increasing the concentration of the low-carbon olefin in the liquefied gas, especially the concentration of isobutene, increasing the ratio of
ethylene to
dry gas, and increasing the
gasoline octane number, and the heavy oil conversion capacity of the main catalyst is not affected when the auxiliary agent is blended in the large proportion manner.