Er-doped silicon-rich Si, were prepared by ion implantation; Silicon nanocrystals, which enwrapped by amorphous Si, were observed when the implanted films were annealed above 900 ℃. The efficiency of PL at 1.54 μm and the microsteucture of the metarial are effected greatly by thermal treatment Er ions lie in amorphous Si and couple with nc-Si through a-Si. The excitation energy from nc-Si to Er was shared by a-Si; At T>150 K, energy back transfer between excited Er and a-Si decreased the PL efficiency. The sample annealed at 1100 ℃ has a rather good emission efficiency.