Abstract: SAPO-34 was undergone by hydrothermal treating with 800 ℃, 100 w% steam for 0-100 h. XRD results showed that the relative crystallinity was decreased with the increase of the hydrothermal treating time. The BET surface area was decreased by 59.6 m²/g and micropore surface area decreased by 95.0 m²/g with treating time increased from 0 h to 100 h. NH₃-TPD indicated that when hydrothermal treating time was between 0~45 h, the total acidities sharply deceased, especially the strong acidities. After 45 h, the change of acidities was little. Fixed bed reaction tests showed that when hydrothermal treating time was between 0~45 h, the catalytic life of SAPO-34 was prolonged over two times, while the selectivity for C₂⁼ + C₃⁼ remained nearly the same with SAPO-34 untreated. After 45 h, the selectivity for C₂⁼ + C₃⁼ was improved greatly but catalyst life didn't chang. The yield of C₂⁼ + C₃⁼ was up to 7.43%.