Abstract: The study focuses on the underground systems of four distinct mixed bamboo forests in Mugan Town, Daguan County, Yunnan Province. These include the natural Qiongzhuea tumidinoda - artificial Phellodendri Chinensis mixed forest(T_Q-Rp), the artificial Qiongzhuea tumidinoda - Phellodendri Chinensis mixed forest(R_QP), the natural Qiongzhuea tumidinoda - Broadleaf tree mixed forest(T_QB), and the natural Qiongzhuea tumidinoda - Camellia reticulata mixed forest(T_QC), to compare the differences in carbon(C), nitrogen(N) and phosphorus(P) contents and their stoichiometric ratios of bamboo whips, roots and root and stem. The results showed that the variations of C contents of Qiongzhuea tumidinoda whips, roots and roots of the test stand ranged from 429.00 to 574.20 g/kg, 313.50 to 429.00 g/kg, and 561.00 to 587.40 g/kg, respectively; the variations of N contents ranged from 6.64 to 18.63 g/kg, 1.40 to 11.88 g/kg, and 4.38 to 15.35 g/kg, respectively; and the variations of P contents were from 6.64 to 18.63 g/kg, 1.40 to 11.88 g/kg, and 4.38 to 15.35 g/kg, respectively. 15.35 g/kg; P content varied from 0.44 to 1.00 g/kg, 0.71 to 1.23 g/kg, and 0.42 to 1.15 g/kg, respectively. There was no significant difference in the C content of the underground system of bamboo among the four Qiongzhuea tumidinoda forest types, while the N and P contents were significantly higher in the two artificial mixed forests than in the two natural mixed forests; The average values of C∶N in the underground system of Qiongzhuea tumidinoda are T_QC > T_QB > T_Q-Rp > R_QP in order; The average values of C∶P and N∶P are highest in T_QB, and lowest in R_QP and T_QC, respectively; Except for T_QB, where the growth and development of underground stems of Qiongzhuea tumidinoda are jointly limited by N and P elements, the growth and development of underground stems of Qiongzhuea tumidinoda in other forest types are only limited by N element. The C content, C∶P, and N∶P in the underground system of Qiongzhuea tumidinoda are primarily influenced by organs, followed by the forest stand. The variation in N and P content, as well as C∶N ratio, primarily originates from the forest stand, followed by organs. It is recommended to apply N and P fertilizers reasonably during the cultivation and management process to improve soil nutrient status and enhance plant nutrient utilization efficiency.