Based on a field experiment involving five precipitation treatments (50% reduction, 30% reduction, control, 30% increase, and 50% increase) and two N addition treatments (0 and 5 g·m^-2·a^-1) conducted in a desert steppe of Ningxia in 2017, the C∶N∶P ecological stoichiometry in both plants and soil microbes were studied, and their relationships with soil C∶N∶P ecological stoichiometry and other indices were also analyzed. Our main objectives were to determine the C∶N∶P balance characteristics both in plants and soil microbes and their key influencing factors. The results showed that: (1) decreasing precipitation had little effects on the C∶N∶P stoichiometry in both plants and soil microbes, reflecting their adaptations to shortterm drought; increasing precipitation decreased N and P contents in both plants and soil microbes, and thus increased C∶N and C∶P. However, these effects were simultaneously influenced by N addition. (2) Under reduced and increased precipitation conditions, N addition had less effect on plant C∶N∶P stoichiometry, whereas it greatly changed soil microbial C∶N∶P stoichiometry, especially under increased precipitation treatments, indicating that precipitation promotes the effect of N addition. (3) Compared with other indices, plant total N content and N∶P and soil microbial biomass N∶P had lower internal stabilities, indicating that these indices could better reflect the N supply and N and P limitation in soils. (4) Among all soil factors, plant C∶N∶P stoichiometry was more affected by available P concentration, phosphatase activity, conductivity, C∶P and organic C content, while soil microbial C∶N∶P ecological stoichiometry more tightly related to conductivity, water content, sucrase activity, and phosphatase activity, indicating that the C∶N∶P ecological stoichiometry of plants and soil microbes are mainly regulated by other soil factors, rather than soil C∶N∶P ecological stoichiometry.