With the instruction of eco-economics theory, ecological planning for small-sized towns, as a macro manipulative one, aims at the harmonious and highly effective development of combined ecosystem of small-sized towns composed of economic system, environmental system and social system. In this paper, large amounts of uncertainties in small-sized towns as well as the ecological planning process are analyzed and the analytical methods for uncertainty are discussed including sensitivity analysis, error function transmission analysis, cybernetics approach and uncertainty mathematical methodologies such as stochastic approach, fuzzy approach, interval algorithm approach, unascertained mathematical approach etc. Based on the uncertainty analysis, it is further proposed the idea of "elasticity planning", which includes the flexibility of planning objective and that of planning scheme. The goal of the idea lies in both the requirement of development of ecological level of small-sized towns and the restriction of various uncertainty factors. In the mean time, the idea has stronger practicability than traditional ecological planning.
