Abstract：Took inhibition ratio of citrus cankor pathogen as investigation target，lixivite dry powder of Amaranthus leaf blades with ethyl acetate and gained Amaranthus tricolor actives．Examined the effect of solidliquid ratio，extraction temperature，and extraction time of Amaranthus tricolor actives by orthogonal experiment．The results indicated that different factors had different degree effects on extraction efficiency．Three extraction parameters were ranked in descending order of their effect on extraction of Amaranthus tricolor actives as follows solid-liquid ratio ＞ extraction temperature ＞ extraction time．Their optimal levels were 1∶5，30 ℃，24 h，respectively．Under these conditions，the inhibition rate was 73.81%．Ultraviolet radiation，C source（sucrose）and inorganic ion（NaCl） stress had little effects on Amaranthus tricolor actives stability．It posses certain heat tolerance，its inhibition rate was still up to 49.41%，when the temperature was 80 ℃．
