To accelerate the early strength of lime-flyash stabilized soil for extending its further uses in highway and shortening highway construction time, five kinds of chemical additives were chosen on the basis of mechanism analysis of accelerating early strength in highway as a semi-rigid base material, and a series of experiments about the effect of different kinds of additives and quantity on the early strength of the stabilized soil were tested. The results show that chemical additives can efficiently improve the early strength of lime-flyash stabilized soil both the 7 d and 28d, and the optimum quantity for above chemical additive is 1.5%-2.5% approximately.Some suggestions for the practical construction were also proposed.