Understanding plant responses to pathogen invasion is important for identifying resistance genes. In this experiment， the seedlings of wheat variety Zhongzuo 9504 were inoculated by powdery mildew， in order to observe the changes of growth， physiological metabolism-related indexes and gene expression in wheat leaves at 0 h， 6 h， 1 d， 4 d and 7 d after infestation. This study attempted to reveal the response mechanism of powdery mildew inoculation on the growth， osmoregulatory substances and reactive oxygen species in wheat. The results showed that with the increase of inoculation time， the number of dead cells， and the activity of peroxidase and superoxide anion in wheat leaves tended to increase. The powdery mildew produced mature secondary conidia 7 days post inoculation. Phenylalanine ammonia-lyase and polyphenol oxidase functioned at different infestation times. Soluble protein content basically showed an increasing trend， chlorophyll content decreased significantly at 7 d， which in turn affected plant growth. No significant changes on hydrogen peroxide content was observed throughout the inoculation period. Transcriptome analysis revealed that PTI signaling was partially inhibited and down-regulated at the initial stage of inoculation （0 h to 6 h）. PTI signaling responded positively in the early and middle stages （6 h to1 d and 1 d to 4 d）， while ETI appeared in the early stage. In the late stage of infestation （4 d to 7 d）， there was a down-regulation tendency on both the PTI and ETI signaling pathways， as powdery mildew had colonized the surface of the leaf completely， thus compromising photosynthesis in wheat.