It is valuable work to construct computational system by means of network, so that its capacity and power can be enbanced and extended. But there is heterogeneity in common among computational systems. It is main obatacle for computational systems to coopetele well. This paper inquires the sound description of heterogeneity for computational systems, and presents several appoaches on definition of heterogeneity. That is significant to go a step further for hiding or exploring heterogeneity in the future.