The objective of this study was to evaluate of nano-zinc oxide and zinc sulfate on thyroid hormones, histomorphometry and microbial in the small intestine. A total of 108 Rose 308 chicks (1d old) were randomly divided into six groups with three replicates per group, each having 18 birds. Treatments include: group one (control with basal diet),group two diet supplemented with nano-zinc oxide 40 mg/kg , group three diet containing zinc sulfate 110 mg/kg , group four subjected to high ambient temperature 40± 2 up to 4 h /day , group five was exposed to high ambient temperature 40± 2 up to 4 h /day and were dietary supplemented with nano- zinc oxide 40 mg/kg , group six was exposed to high ambient temperature 40± 2 up to 4 h /day and were dietary supplemented with zinc sulfate 110 mg/kg. The results showed a significant increase in thyroid hormones and thyroid stimulating hormone (TSH), villi height, villi width, crypt height, crypt width, goblet cell, apparent surface area, Lactobacillus population with a reduction of E. coli in nano-zinc oxide and zinc sulfate compared with control and height ambient temperature. It was concluded that nano-zinc and zinc sulfate improved thyroid function, intestinal morphology and microbial populations in broiler.