Template agent is an essential part in the synthesis of molecular sieves, which has great influence on the physical properties and catalytic properties of molecular sieves. SAPO?34 molecular sieve was synthesized by hydrothermal method using stainless steel tube as crystallization vessel. The effect of PEG?800 addition on crystallinity, morphology and acidity of molecular sieve was investigated, and its MTO catalytic performance was evaluated. The results show that the molecular sieve samples synthesized with TEAOH & PEG?800 as the composite template agent are thin plate?like, the crystallinity and acidity are suitable, and the longest catalytic life is 340 min. When the methanol conversion is above 95%, the selectivity of diolefins is up to 84.0%. It is also found that the thinner the crystal thickness of the lamellar molecular sieve, the better the catalytic performance.