The study was conducted at the chicken farm in Soc Son district, Hanoi from March to August 2022 to evaluate carcass traits and meat quality of crossbred [Ri × (Ri × Luong Phuong]) broilers fed herbal feed additives in order to determine the appropriate time for slaughter. 30 broilers were slaughtered at 3 different ages (15, 20, and 25 weeks old) with 10 birds (5 males and 5 females) at each time for evaluation. The results showed that the final weight, carcass percentage, weight and percentage of some visceral organs (gizzard, liver, abdominal fat, …) were affected by slaughtered age (P <0.05), values increased with increasing slaughtered age. Most indicators related to carcass traits were influenced by sex (P <0,05), and males were greater than females, except breast meat and abdominal fat of females were higher than males. Shear force and color values (L*, a*, b*) of breast meat and drip loss of thigh meat were affected by slaughtered age (P <0.05), with an increase in a* value and shear force, and a decrease in L* with increasing age. pH24, drip loss, and b* of thigh meat were influenced by slaughtered age (P <0.05). Moreover, slaughtered age impacted dry matter, crude protein, lipid, and ash of breast meat (P <0.05).Crude protein increased while lipid decreased with increasing slaughtered ages.The cholesterol content of breast meat was affected by sex (P <0,05), female values were higher than male ones.