Fallen log decomposition is an important process of carbon and nutrient cycling in most of forest ecosystems. The previous studies have found that the recalcitrant the components in fallen log positively promoted the soil organic matter accumulation. However, the effects of forest gap positions and epiphytes removal on the concentrations of resistant material in fallen log remain unclear. Thus, we conducted a field experiment to explore how the gap regeneration and epiphytes removal influence the total phenols and condensed tannins during the dead wood degradation in an alpine Minjiang fir (Aibes faxoniana) forest in western Sichuan from August 2013 to August 2016. We sampled from two treatments (removal and retention of epiphytes) with different fallen log structures (heartwood, sapwood and bark) of five decay classes (I-V) in three gap positions (gap center, gap edge and closed canopy). The total phenols and condensed tannins concentrations were measured. The results showed that the concentrations of total phenols and condensed tannins in bark were significantly higher than those of heartwood and sapwood. The concentrations of total phenols and condensed tannins in decaying bark varied slightly with different decay classes. Gap positions gave strong effects on the concentrations of total phenols in Ⅲ-V decay classes of heartwood and sapwood, that is to say, the concentrations of total phenols in Ⅲ-V decay classes of heartwood and sapwood varied greatly with gap position. However, no significant difference of condensed tannins in heartwood and sapwood was observed among gap positions. The gap positions exerted extremely significant effects on the concentrations of total phenols and condensed tannins in decaying bark, and the values in the order of concentrations were, gap center > gap edge > closed canopy. The epiphytes removal lowered the concentration of condensed tannins in decaying heartwood and the concentration of total phenols in decaying sapwood, but increased the concentration of condensed tannins in decaying sapwood. The interaction of epiphytes and gap positions significantly affected the concentrations of total phenols and condensed tannins in decaying bark. In gap edge and closed canopy, epiphyte removal significantly lowered the concentrations of total phenols and condensed tannins in decaying bark. Additionally, the changes in temperature resulted from gap position was a major driver of the concentrations of total phenol and condensed tannins in decaying bark. Moreover, the change of log pH resulted from epiphytes removal might also be one of the reasons of the differences of concentrations of total phenols and condensed tannins in fallen log. Together, gap regeneration and epiphytes can regulate the concentrations of recalcitrant components in decaying fallen log in the alpine forest. The results provided with new insights for us to understand the roles of forest gap and epiphyte in carbon and nutrient cycling in fallen log decomposition.