Abstract: The relationship between Li-Yorke chaos and distributional chaos in a sequence is discussed. It is pointed out that the set of distributional \delta-scramble pairs in a sequence Q is a G_\delta set, and Li-Yorke \delta-chaos is equivalent to distributional \delta-chaos in a sequence. A uniformly chaotic set is a distributional scramble set in some sequence and a class of transitive system implies distributional chaos in a sequence.