Abstract: Based on a series of data analyses, numerical simulations and theoretical studies, comprehensive discussions of some fundamental problems of intraseasonal oscillation in the tropical atmosphere are carried out in this paper. They include the regional location feature, spatial scale feature and horizontal propagation of 30-60 day oscillation; the relationship with intraseasonal oscillation in the mid-high latitudes; the interaction between E1 Nino and tropical intraseasonal oseillation and some dynamical mechanisms which excite tropical atmospheric intraseasonal oscillation. Throubrh these analyses and diseussions, it is hoped to have deeper and better-defined under standing of the intraseasonal oscillation in the tropical atmosphere.