The nitrogen/hydrogen (N-2/H-2) plasma-treated strontium titanate (SrTiO3 ) crystals with different orientations of (111), (110) and (100) were obtained using microwave plasma chemical vapor deposition, which was proved to be a simple and effective strategy to fundamentally improve the photocatalytic performance. It is found that plasma-treated SrTiO3 crystals exhibit different photocatalytic properties in relation to crystalline anisotropy, plasma types and microwave power. The N: SrTiO3 samples display higher photocatalytic activity compared to the untreated sample and N-2/H-2 -treated sample. The (111) N: SrTiO3 which is treated using N-2 plasma of 600 W shows the best photocatalytic performance in the current research. The dopants of nitrogen can serve as electron donors, which introduce impurity states in various positions in the band gap of SrTiO3 and lead to different degrees of modification in electrical conductivity. The enhancement for photocatalytic properties and the effects of N-2 plasma treatment on the charge separation and transfer efficiency will be discussed.