In order to study the effects of whole soil-plastic mulching planting and different fertilization rates on soil water consumption characteristics and yields of tartary buckwheat, a three-year (2015-2017) located experiment was carried out in semi-arid region of east-central Gansu Province, China, under whole soil-plastic mulching planting system. Four fertilization treatments under soil-plastic mulching were accordingly designed, including high application rate (HF, N 120 kg hm-2+ P2O5 90 kg hm-2 + K2O 60 kg hm-2), medium rate (MF, N 80 kg hm-2+ P2O5 60 kg hm-2 + K2O 40 kg hm-2), low rate (LF, N 40 kg hm-2+ P2O5 30 kg hm-2 + K2O 20 kg hm-2), and zero fertilization rate (ZF), whereas ZF with traditional non-mulching planting was set as the control (CK) to illustrate the effects of soil-plastic mulching and fertilization on water consumption characteristics, yields and water use efficiency (WUE) of tartary buckwheat in semi-arid area of China. The results showed that the effects of rainwater collection and soil moisture conservation were obvious after planting tartary buckwheat with whole soil-plastic mulching, which also improved soil water environment and increased pre-anthesis soil water storage (SWS, mm). LF was able to regulate soil water consumption before and after anthesis stage according to different precipitation years and soil moisture conditions. Compared with ZF, MF, HF, and CK in dry years, LF improved post-anthesis SWS by 2.8-23.5 mm and increased crop pre-anthesis water consumption in the 0-100 mm soil profile by 26.3-32.4 mm in tartary buckwheat. As a result, LF increased total crop water consumption in the whole growth period by 44.5 mm, and boosted water consumption module coefficient and intensity. Moreover, compared with ZF, MF, HF and CK, LF treatment increased dry matter weight at maturity stage by 1.2%-58.8%, leaf area index (LAI) at filling stage by 4.1%-68.5%, grain weight per plant by 1.6%-61.6%, plumpness rate by 0.6%-29.2%, biomass yield by 1.1%-182.5%, grain yield by 1.1%-130.4%, and water use efficiency (WUE, kg hm-2 mm-1) by 0.3%-102.7%, respectively. In conclusion, the storage effect of low amount fertilizer treatment for tartary buckwheat planting with whole soil-plastic mulching in dry land was obvious, which could achieve the coupling effects of soil moisture and fertilizer and regulate crop water consumption according to the environmental conditions such as precipitation during crop growth period, and it could significantly improve the biomass yield, grain yield and WUE of tartary buckwheat. Therefore, it was a suitable cultivation mode for yield-increasing and efficiency-boosting of tartary buckwheat in semi-arid area.