Based on the model of Fertilization Environmental Safety Threshold and data from 2002～2016，this paperestablished the method of assessing rational use ofNitrogen(N)，Phosphate(P 2O5)andPotash(K 2O)fertilizers(NPK)to measure and analyze the features，environmental safety thresholds and ecological rationalities of NPK fertilizer consumptionin three countries ofChina，Kazakhstan and Germany under the“the belt and road initiatives”for helping them to makeright polices of fertilizers consumption and agricultural development strategies，and improve international cooperation.The results showed that the fertilizer consumption of China went up to the top and started to decline，Kazakhstan wasincreasing，and Germany slightly decreasing with fluctuation from 2002 tO₂016，respectively；the FertilizationIntensity of three countries changed from278.0，1.62，272.2 kg/hm²in 2002 to332.5，7.47，265.2 kg/hm² in 2016 bythe growth of20%，360%，-2.6%，respectively；the proportion of N to P to K changed from 1∶0.42∶0.31，1∶0.85∶0.02，1 ∶ 0.18 ∶ 0.27 in 2002 to 1 ∶ 0.51 ∶0.45，1 ∶0.36:0.03，1 ∶ 0.14 ∶ 0.26 in2016，respectively；the FertilizationEnvironmental Safety Threshold for each country was 227～272，96～120，323～ 373 kg/hm² during the period of 2002tO₂016，respectively. In terms of ecological rationality of NPK fertilizerconsumption，China was on the second level(relativerational)，Kazakhstan the fourthlevel(irrational)，and Germany the firstlevel(rational)for N fertilizeruse.This paper which sets up a new method to evaluate ecological rationality of fertilizer consumption would help three countries under“thebelt and road initiatives”improve their fertilizer use. As forChina，it is urgently to reduce the amount of fertilizers use to the proper level for the environmental safety by learning from Germany’s experiences of eco-agricultural industrialdevelopment， and there are prospective markets for China to strengthen the international agriculture co-operations with Kazakhstan.