[Objective] The objective of the study is to explore the effect of monosodium glutamate wastewater manure(hereinafter referred to as manure) mixed with inorganic fertilizer on the root absorption characteristics and humus composition of rhizosphere soil of watermelon(Citrullus lanatus).[Methods] The present study was conducted to determine the effects of different treatments, i.e. CK(control, no fertilization); N₁₀₀(pure urea, hereinafter referred to as inorganic fertilizer); M₁₀N₉₀(the proportion of manure and inorganic fertilizer is 10% and 90%); M₃₀N₇₀(the proportion of manure and inorganic fertilizer is 30% and 70%) and M₅₀N₅₀(the proportion of manure and inorganic fertilizer is 50% and 50%) on root activity, construction levels of root system, root morphological characteristics and root exudates, as well as humus composition in the rhizosphere soil of watermelon.[Results] The results indicated that in comparison to N₁₀₀ treatment, M₃₀N₇₀ treatment significantly increased root activity, and promoted the root growth of watermelon. At the same time, M₃₀N₇₀ treatment also increased the total root length, root surface area, specific root surface area, root volume and root tip number, while the root average diameter obviously decreased. The total root length in the M₃₀N₇₀ treatment increased by 74.63%, 40.84%, 28.41% and 19.37%, and the specific root surface area was increased by 39.42%, 30.82% and 20.89% compared to the treatments of CK, N₁₀₀, M₁₀N₉₀ and M₅₀N₅₀, respectively. In addition, M₃₀N₇₀ treatment obviously increased the contents of root exudates and humic acid, and increased the ratio of humic acid to fulvic acid, showing 137.36%, 47.95% and 33.33% increase in humic acid content compared with the treatments of CK, N₁₀₀ and M₁₀N₉₀, respectively. However, in M₁₀N₉₀ and M₅₀N₅₀ treatments, less effects was observed than that in M₃₀N₇₀ treatment.[Conclusion] Monosodium glutamate wastewater mixed with inorganic fertilizer, especially M₃₀N₇₀ treatment, is beneficial to the root absorption characteristics and humus composition in the rhizosphere soil of watermelon, and it is recommended as the suitable fertilization proportion in the practice.