Abstract. Variations of precipitation and temperature at Lake Qinghai, NE Tibetan Plateau on decadal scales during the past 800 years were reconstructed based on the oxygen isotope values and Li/Ca ratios from ostracod shells of the single species Eucypris inflata. Higher temperature relates to lower Li/Ca ratios; higher precipitation relates to lower δ¹⁸O values, and vice versa. The good correlation between Li/Ca ratios and δ¹⁸O values of ostracod shells indicates that temperature variations corresponded well with precipitation variations on decadal scales during the past 800 years. Variations of precipitation and temperature are synchronous with variations of solar activity reconstructed from the atmospheric ¹⁴C concentration in tree rings and the ¹⁰Be concentration in ice cores. These findings suggest that, on decadal scales solar activity may be responsible for the synchronous variations of precipitation and temperature at Lake Qinghai, NE Tibetan Plateau during the past 800 years. Keywords: Precipitation variations; Temperature variations; Eucypris inflata; Li/Ca; δ¹⁸O; Synchronous variations; Lake Qinghai; Solar activity.