A series of samples La 2-xSr xCuO 4 (x=0.17∼0.33) were prepared using solid state reactions and then annealed at 500°C and 700°C in flowing nitrogen. After annealing, the crystal structure and lattice parameters of the samples show little changes, but T c's for samples with x>0.19 show significant changes. The ac susceptibility measurement indicates that two plateaus exist in the T c versus x curves of the annealed samples. The first plateau occurs with T c around 35K in the x range from 0.17 to 0.23 and, and the second one occurs with T c around 29K when 0.23<x<0.29. A possible reason is given to explain this interesting phenomenon based on phase separations.