SAPO-11/HBeta composite was synthesized by using hydrothermal method (SB-H) and applied as catalyst for cracking of 2-butylene to C-2-C-3 olefins. SB-H sample exhibited comparatively high selectivity and high yield of C-2-C-3 olefins. XRD, IR, Al-27 and P-31 MAS NMR, Py-IR characterizations indicate that defect structure P(AlO4) (n) (n < 4) really existed in SB-H sample. SAPO-11 and HBeta chemically bonded and the defect P(AlO4) (n) (n < 4) formed during the hydrothermal synthesis of SB-H sample. P(AlO4) (n) (n < 4) unit caused new B acidic sites, which increased B acidic amount and B acidic distribution on SB-H sample. The improvement of B acidity decreased apparent active energy of cracking of 2-butylene to C-2-C-3 olefins on SB-H sample. Therefore, the high selectivity and high yield of C-2-C-3 olefins were obtained on SB-H sample in catalytic cracking of 2-butylene.