Abstract: In order to clarify the effect of padding on the growth of Escherichia coli in the fermentation bed for pig raising under natural conditions, the growth of Escherichia coli in padding was studied. The green fluorescent protein (GFP)-labeled Escherichia coli K₈₈ was inoculated into the padding of microbial fermentation bed for pig raising by using the method of artificial inoculation. The growth dynamics of Escherichia coli K₈₈-GFP in the padding were observed by using the plate isolating culture method. The results showed that Escherichia coli K₈₈-GFP could grow well both in the fresh padding with bactericidal treatment and the old padding used for one year, and the contents of Escherichia coli K₈₈-GFP reached 4.03×10⁸ cfu·g^-1 and 5.37×10⁸ cfu·g^-1 after 168 h of isolating culture, respectively, with no significant difference in order of magnitudes. However, Escherichia coli K₈₈-GFP could not grow in the fresh padding without bactericidal treatment and the old padding used for one year. The results indicated that the padding of microbial fermentation bed for pig raising could inhibit the growth of Escherichia coli K₈₈ in the natural environment.