Stand types affect the efficiency of negative air ions generation within forest communities. However,the key driving factors of negative air ion concentration (NAIC) in different stand types remain unclear. This study selected four primary stand types within Xinjiang's mountainous forest: coniferous and broad-leaved mixed forest,evergreen coniferous forest,deciduous coniferous forest,deciduous broad-leaved forest,with non-forest land serving as the control group. NAIC and 10 environmental factors-including air oxygen content,airborne bacteria content,PM_2.5 concentration,PM₁₀ concentration,light intensity,ultraviolet radiation intensity,temperature,relative humidity,wind speed,and air pressure-were monitored. Finally,the key driving factors of NAIC in different stand types were identified by path analysis. The results revealed that (1) Significant differences in NAIC were observed across stand types,with coniferous and broad-leaved mixed forest ((3072±385) ions/cm³) having the highest NAIC,followed by evergreen coniferous forest,deciduous coniferous forest,deciduous broad-leaved forest,and non-forest land. (2) In the coniferous and broad-leaved mixed forest,relative humidity was identified as the primary determinant of NAIC,with ultraviolet radiation intensity exerting strongest direct positive influence on NAIC,and the indirect negative effect of PM_2.5 concentration on NAIC through relative humidity was notably significant. (3) In the evergreen coniferous forest,relative humidity served as the paramount environmental factor influencing NAIC. Air pressure had the most pronounced direct positive impact on NAIC,while ultraviolet radiation intensity contributed the largest indirect positive effect. Furthermore,temperature's indirect negative influence on NAIC,mediated through relative humidity,was also remarkable. (4) In the deciduous coniferous forest,ultraviolet radiation intensity was the key driving factor of NAIC. Moreover,the direct negative influence of airborne bacteria content on NAIC was the most prominent,while the indirect positive effect of relative humidity on NAIC was equally significant. (5) In the deciduous broad-leaved forest,light intensity was identified as the primary determinant of NAIC. PM_2.5 concentration had the most substantial direct negative impact on NAIC,while relative humidity displayed the most prominent indirect promoting effect on it. (6) In non-forest land,NAIC was predominantly controlled by PM_2.5 concentration. Air pressure stood out as the most direct positive factor affecting NAIC,while PM₁₀ concentration had the largest indirect negative effect,and the relative humidity indirectly promoted NAIC. Therefore,the influencing factors of NAIC across various stand types exhibit both commonalities and differences,with relative humidity having a significant influence on NAIC across diverse stand types. Through path analysis,this study elucidates the action pathways and the comprehensive determining effects of environmental factors on NAIC,providing a theoretical foundation for identifying the key driving factors of NAIC in different stand types.