The design of Satellite Constellation is one of the important steps to carry out space missions. This paper focuses mainly on the problem of how to design δ constellation effectively. The method, which is used to analyse the covering condition of some area with many satellites at one certain time, is discussed and certified. Based on this method, δ constellation is analysed by the means of simulating calculation. The method to design δ constellation is given at the end of the paper, and some δ constellation, which are designed by this method to fulfill some special needs, are listed.