The research aimed to identify The effect of eccentric training with 2/1 technique on developing some special physical abilities and lower body asymmetry for Taekwondo cadet under 14 years old . the researchers used the experimental method for a sample of (18) cadet from the taekwondo team in the Employees club at Zagazig University.They were divided into two groups, one experimental and the other a control group, each group consisted of (9) players. The researchers used the following statistical treatments: the mean - the standard deviation - the median - the torsion coefficient - the "T" test - the correlation coefficient - the equation of improvement rates- Mann-Whitney test - percentages of improvement - Cohen's test (d) to measure effect size (low effect ≥ 0.2, medium effect ≥ 0.5, large effect ≥ 0.8). Among the most important findings and conclusions: - The use of eccentric training with 2/1 technique is positively influences development of some special physical abilities (acceleration, special Agility, power, maximal muscle strength, speed, Kinetic balance, muscular endurance, power endurance ) for Taekwondo cadet. - The use of eccentric training with 2/1 technique is positively influences development of lower body asymmetry for Taekwondo cadet. The researchers recommends the importance of: - use eccentric training with 2/1 technique to development The physical abilities of athletes in various sports activities for different age groups during different season periods. - The use of the tests used in this research when measuring the physical abilities of Taekwondo and determining the asymmetry index.