Background and aims <p>Soil microbial communities are crucial for ecosystem functioning, but their seasonal responses to climate warming and increased precipitation are poorly understood. This study investigates how soil microbial communities respond to warming and enhanced precipitation across different seasons in a semiarid grassland.</p> Methods <p>A field manipulation experiment of climate warming and increased precipitation was conducted to assess seasonal variations in bacteria and fungi composition and diversity in a semiarid grassland of Inner Mongolia. We analyzed bacterial and fungal communities by sequencing the 16S rRNA and ITS regions.</p> Results <p>Warming changed asynchronously bacterial composition in each period of growing seasons and increased fungal species richness in early growing season. In contrast to warming, increased precipitation differentially changed bacterial and fungal composition in each period of growing season. Structural equation models showed that warming lowered bacterial diversity by increasing air temperature in late growing season, but did not change fungal diversity. Increased precipitation limited bacterial diversity by inhibiting soil organic carbon in early growing season and soil moisture, total nitrogen and plant diversity in late growing season. Conversely, increased precipitation also increased fungal diversity through enhancing soil pH and plant diversity in early growing season.</p> Conclusions <p>These findings demonstrate asynchronous responses of microbial community in different seasons to climate warming and increased precipitation, with subsequently reconstruct the seasonal pattern in microbial communities.</p>