Abstract: The Lewis acid catalyst——aluminium chloride was first used as catalyst for cyclization of pseudoionone in this study. Catalyst can effectively promote cyclization of pseudoionone. The process had characters of mild condition,simple post-processing and easy operation. The optimum conditions were determined as follows:temperature 0℃,mass ratio of AlCl3 to pseudoionone 3:4,reaction time 3h.The constituents of product were determined by GC-MS. Using AlCl3 as catalyst,pseudoionone was synthesized into β-ionone and dihydro-α-ionone.The yields of β-ionone and dihydro-α-ionone were 45.54%and 43.55%,respectively. The conversion rate of pseudoionone was 96.00%.In addition,the catalyst of high activity could be reused repeatedly. The process gives no pollution and has characters of green synthesis.