Degradation line of cypermethrin were studied in different samples of tomato fruits, water, and soil from ogla oasis in the desert environment of Cyrenaica, -Libya. The targeted insecticide was applied to the tomato crop, water, and soil of the studied area with the recommended dose. Representative samples from all three subjects were taken daily which started from the first day of treatment to the 20 th days of experimentation. Extraction and cleanup were conducted on the 20 th days and finely detection of the residues was measured by using Gas chromatography (GC-ECD) instrument. Results of the study revealed 0.06, 1.06, and 2.44 ppm insecticide concentration on the first sampling date from tomato fruits, water, and soil respectively. However after one week 33, 56 and 65% reduction in insecticide concentration was reported in tomato fruits, water and soil respectively. After 2 weeks the reduction percentage was reported 66%, 88%, and 93% chronologically, and the degradation exert 91%, 97%, and 99.1% in the same order at the last sampling date. Results concluded that the trends of cypermethrin degradation were fluctuating and slow in tomato fruits while in water and soil it appears regular. However the degradation in soil was the fastest.