Land resources are essential natural resources and strategic economic resources for human survival and development. However, human improper use has brought unprecedented pressure and challenges to the ecosystem. Therefore, the assessment and analysis of land ecological security status and the identification and diagnosis of obstacles affecting land ecological security are helpful to avoid land ecological security problems caused by improper land use at the source and provide a theoretical basis for the sustainable use of land resources and the construction of ecological civilization in China. Based on the data from 2006 to 2020, this study constructed the land ecological risk-evaluation index system and land ecological health-evaluation index system. AHP, entropy method, combination weighting method, TOPSIS model, Boston matrix and obstacle degree model were used to assess the land ecological security situation in Nanyang City and to analyze the obstacle factors. The results show the following: (1) during the study period, the land ecological risk value of Nanyang City exhibited a Kuznets inverted “U” curve change, while the land ecological health value showed a “U” curve change; (2) the overall level of land ecological security in Nanyang City has gradually improved, with a security level pattern of “relatively safe (2006–2020)–unsafe (2011–2016)–relatively safe (2017–2019)–safe (2020)”; (3) the main obstacle factors of land ecosystem were the following: erosion area, sewage discharge, area of waterlogging control, grain sown area, coverage of urban green built-up area and farmland effective irrigated area.