By using heat-resisting,late-maturing purple pepper‘7036’and heat-sensitive,early-maturing green pepper‘9050’,we studied the effects of heat stress on POD isozyme and DNA methylation expression.The results indicated that:(1)as for POD expression,one more band existed in treatment without heat stress in pepper‘7036’,and different change tendency of POD activity existed in two peppers.(2)With the time extending,percentage of non-methylation and full-methylation increased,whereas percentage of half methylation and total methylation decreased in pepper‘7036’,and only percentage of methylation in the treatment of heat stress for 7 days(T₇) showed similar changing tendency in pepper‘9050’,while its absolute values of full-methylation and half methylation ratio were significantly less than those of‘7036’.(3)As regards to methylation profiles of T₇ treatment,higher ratio of C type band of hypomethylation existed in pepper‘7036’and B type band of hypermethylation showed in pepper‘9050’.The results above showed that,recovery of POD activity,declining in percentage of half methylation and rising in percentage of full-methylation rapidly,and hypomethylation were relevant to resisting heat stress in purple pepper‘7036’.