Abstract: To enhance herbicide efficacy, this study investigated the effects of an isomeric alcohol ether synergist YC005 on the biological activity and mechanisms of two commonly used wheat field herbicides: diflufenican and isoproturon. The herbicidal activity of these herbicides, mixed with varying concentrations of YC005, against Aegilops tauschii Coss and Aegilops cylindrica Host was determined. Instrumental analyses were conducted to assess the effects of YC005 on the dynamic/static surface tension, contact angle, spread area on leaves, evaporation time, and deposition distribution of the active ingredients. The results showed that the ED₅₀ values of diflufenican and isoproturon mixed with different doses of YC005 against Aegilops cylindrica Host ranged from 24.69 to 30.50 g a.i./hm² and 183.75 to 218.98 g a.i./hm², respectively, representing a 1.21- to 1.84-fold reduction compared to the herbicides applied alone. The ED₅₀ values against Aegilops tauschii Coss were 33.40-38.26 g a.i./hm² and 87.82-96.15 g a.i./hm², respectively, which were 1.85-2.67 times lower compared to the herbicides used alone. Mechanistic studies revealed that YC005 significantly decreased the initial and equilibrium dynamic surface tension of diflufenican and isoproturon solutions by 44.4%-58.9% and 51.6%-57.1%, respectively. Static surface tension and contact angle were also markedly reduced, with decreases of 32.4%–36.1% and 36.8%-54.4%, respectively. The spread area of the herbicide solutions increased by 34.5- to 39.1-fold, and the evaporation time was shortened by 4.7- to 5.5-fold, while the comprehensive index λ was significantly enhanced. Furthermore, YC005 enhanced the wetting, spreading, and subsequent absorption of the herbicide solution on the target leaves in a dose-dependent manner. In conclusion, the synergist YC005 significantly enhanced the herbicidal efficacy of both herbicides by improving the wetting and spreading properties of the spray solution. These findings provide a scientific basis for optimizing application strategies to reduce herbicide dosages while ensuring effective weed control.