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Land degradation is one of most serious socio-ecological problems in Northeast Asia dryland regions (NADR), which requires reliable assessments on degree and extent of land degradation. This paper aims (1) to assess the applicability of Rainfall Use Efficiency (RUE) and Precipitation Marginal Response (PMR) in monitoring land degradation in NADR, and (2) to analyze natural factors for land degradation. Using AVHRR NDVI data for the period of 31 years from 1982 to 2012, we combined RUE and PMR trend analysis to assessing potential land degradation in NADR. Various climate factors (i. e., temperature and precipitation) were utilized to determine natural factors of land degradation. Our results showed that: (1) Land degradation mostly occurred in some part of Xinjiang, Inner Mongolia and Gansu; improved areas are mostly distributed in agro-pastoral transition zone in China; (2) Climate factors partly explain the trend of land degradation. In NADR, precipitation could not fully explain the patterns of vegetation dynamics. The increased NPP were related to temperature in transition zone of China.