To explore the characteristics and influencing factors of the surface negative air ion concentration (NAIC) of urban remnant mountains (URMs) in karst areas, 22 URMs in the built-up area of Guiyang were taken as the research objects, and the spatial pattern characteristics of the surface NAIC of URMs were analyzed through the method of sample plot survey. In addition, we used one-way ANOVA, Pearson correlation, and multiple linear regression to analyze the effects of mountain size, mountain patch characteristics, average mountain vegetation cover, plant species diversity, plant community volumetric biomass, surface radiation, air temperature, humidity, human disturbance, near-infrared radiation, short wave near-infrared radiation and urban landscape pattern around URMs on the surface NAIC. The results showed that:(1) the order from high to low of surface NAIC of URMs of different sizes was medium URMs, small URMs, and large URMs. There was a two-level pattern in which the surface NAIC of URMs on the eastern and northern slope direction was larger than the western and southern slope, but slope position of same slope direction had no significant relationship with the surface NAIC of URMs. (2) The surface NAIC of URMs were highly significantly negatively correlated with the mountain surface temperature and significantly positively correlated with the mountain surface air humidity. The effect of plant community volume biomass on the surface NAIC of URMs was greater than other influencing factors and was most significant in small URMs. Plant species diversity had a weak effect on the surface NAIC of URMs, with the Margalef index having the greatest effect. (3) The surface NAIC of large URMs had a correlation with human disturbance, average elevation, landscape shape index and surface radiation of URMs. Human disturbance, slope difference and surface radiation of URMs had a significant influence on the surface NAIC of medium URMs. However, patch characteristics of URMs had no significant relationship with the surface NAIC of small URMs. (4) The influence range of the surrounding environment on the surface NAIC of large URMs was 300 m, while for medium URMs and small URMs was 500 m. Watershed-related indicators in the surrounding environment had the greatest influence on the surface NAIC of large URMs and medium URMs, and indicators related to URMs in the surrounding environment had the greatest influence on the surface NAIC of small URMs. Investigating the influence of the external and internal environment on the surface NAIC of URMs in karst areas is conducive to enriching the study of negative air ion in karst areas and providing a scientific reference for ecological recreation and mountain tourism planning.