To study the effect of light application time on genomic DNA methylation in rice field eel (Monopterus albus),three light application time (8 h,10 h,12 h) were arranged and the genomic DNA methylation patterns of seven tissues ( heart,liver,muscle,brain,spleen and kidney) were analyzed by MSAP ( methylation sensitive amplified polymorphism) technology.The results showed that different tissues had different methylation patterns among three treatments.The muscle was sensitive to light application time,in which total DNA methylation was significant different among three treatments and hemimethylation of 12 h treatment was significant different.Both the Kidney and brain were not sensitive to light application time,with no significant differences found in hemimethylation,methylation and total methylation among three treatments.Complicated changes were found in the liver,intestine,spleen and heart.In the liver,no significant differences of hemimethylation and total methylation were found among three treatments,while methylation of 8 h was significant different from the other two treatments.In the intestine,no significant differences of hemimethylation and methylation were found among three treatments while significant change of total methylation was found between 10 h and the other two treatments.In the spleen,significant differences of hemimethylation and total methylation were found between 10 h and 8 h treatments,while hemimethylation of 12 h was different from the other two treatments.In the heart,significant differences of hemimethylation were found in the treatment of 10 h.