  We synthesized Sr-doped $La_{0.85}Sr_{0.15}OFeAs$ sample with single phase,
and systematically studied the effect of oxygen deficiency in the Sr-doped
LaOFeAs system. It is found that substitution of Sr for La indeed induces the
hole carrier evidenced by positive thermoelectric power (TEP), but no bulk
superconductivity is observed. The superconductivity can be realized by
annealing the as-grown sample in vacuum to produce the oxygen deficiency. With
increasing the oxygen deficiency, the superconducting transition temperature
($T_c$) increases and maximum $T_c$ reaches about 26 K the same as that in
La(O,F)FeAs. TEP dramatically changes from positive to negative in the
nonsuperconducting as-grown sample to the superconducting samples with oxygen
deficiency. While $R_H$ is always negative for all samples (even for Sr-doped
as grown sample). It suggests that the $La_{0.85}Sr_{0.15}O_{1-\delta}FeAs$ is
still electron-type superconductor.
