This paper addresses development of the conceptual design program of satellite communication system. A database for more than 200 small satellites of LEO which are between 10kg and 200kg was constructed to conduct a sequential process of conceptual design. General parameters based on the database were derived to be able to use for initial design of satellite communication system. The general conceptual design process developed and programed in this work is applicable to micro-class small satellites without regard to mission types. This conceptual design algorithm is consisted of five sequential steps, in which various parameters are defined every phase. These parameters are utilized for conceptual design through database analysis. The validity of an entire design algorithm has been demonstrated via program simulation.