The Paris Agreement established a long-term goal of holding the increase in the global average temperature to well below 2℃ and pursuing efforts to limit the temperature increase to 1.5℃ by the end of this century. Therefore,properly assessing and comparing national NDC mitigation ambitions would be a main content in global stocktake,which is important to the considerations of enhancing efforts to close the emissions gap with 2℃ and 1.5℃. To this end,this paper assesses the NDC ambition of China,India,Brazil, South Africa,the USA,EU - 28,Japan and Russia,respectively,by applying emissions allowances allocated by 16 effort-sharing approaches under selected 2℃ and 1.5℃ pathways. Results demonstrate that,the NDCs of developed countries generally locate above or in the upper-ends of the 2℃ - consistent ranges of emissions allowances and present even big gaps with the 1.5℃ - consistent ranges,implying developed countries need to ratchet up the NDCs and take the lead in elevating the level of mitigation. An assessment based on cumulative emissions,compared against that based on 2030 emissions,is more likely to clarify the ambition and fairness of China's NDC. The projected NDC emissions of China meet the median of cumulative allowances under 2℃ and align with the 1.5℃ - consistent ranges. The Paris Agreement also invited the Parties to communicate,by 2020,the mid-century,long-term low emissions strategies. To hold mid-century emissions within calculated 2050 emissions allowances,our allocations find that China might need to reduce CO_2 emissions by over 42% and 65% from the 2010 levels under 2℃ and 1.5℃,respectively by 2050. The corresponding annual mitigation rates,from 2030 to 2050,are at least 3.0% and 5.3% in average,respectively. These might help China's decision-makers consider the 2050 mitigation targets.