Studies on land degradation and development (LDD) and the underlying factors can help land restoration. In this study, the LDD of Hainan Island from 2000 to 2018 were measured by change vector analysis using the normalised difference vegetation index and net primary productivity (NPP). The underlying factors of LDD were selected from seven potential factors (nature factors: mean annual temperature, mean annual drought intensity, human disturbances: gross domestic product (GDP), population, population urbanisation, accumulated afforestation area, construction area) based on structural equation modelling. The results showed that 1) the degree of land-use changes into water area and construction land were higher than for the other land-use types; 2) Compared to 2000, the most serious degradation occurred in 2015, which accounting for 68.98% of the total land degradation as well as more than three-quarters of the land degradation in all surveyed years was driven by NPP; 3) The proportion of land degradation (PLD) was negatively correlated with the mean value of the land degradation and development (MLDD) in the period of five years, 2000-2018 (P<0.01); 4) The key influencing factors of PLD were temperature, accumulated afforestation area, population urbanisation, in 2000–2005, 2005–2010 and 2010–2018, respectively; 5) The key influencing factors of MLDD were temperature, GDP, population urbanisation, in 2000–2005, in 2005–2010 and in 2010–2018, respectively. Therefore, to minimise land degradation it is necessary to limit the speed of population urbanisation occurs and to improve the island environment’s adaptability to extreme climates.