Spirulina platensis alga is an extreme protein source that enhances ovarian function and diminishes heat stress impacts. This work aims to study the enhancement effect of Nano-Spirulina-platensis alga on female rabbit puberty and its ameliorative effect against adverse effects of heat stress (HS). HS impairs growth and delays the puberty of rabbits. Spirulina-nanoparticles were prepared then; HPLC, antioxidant DPPH, total phenolic, and flavonoids were estimated. 24 New Zealand female rabbits were divided into 4 groups (n=6). G1 negative control group under ambient temperature. G2 was exposed to heat stress(35°C). G3 and G4 were dietary supplied with Nano-Spirulina (15mg and 35mg/Kg bwt/30 days under heat stress respectively. Rabbits' body temperature, respiration rate, body weight gain, feed intake, food conversion rate(FCR), feed efficiency ratio(FER), and puberty behavior observation were recorded. Blood plasma was collected and analyzed for the reproductive hormones; follicle-stimulating hormone(FSH), luteinizing hormone(LH), and progesterone(P4). Also the proliferative marker Transforming-Growth-Factor-Beta-2 (TGFβ2), and the cytokines as; Gamma-Interferon(INFγ), Interlukine-1(IL-1), and Tumor-Necrosis-Factor α(TNFα). In addition to the liver and renal function markers Albumin, Alanine-Transaminase(ALT), Aspartate-aminotransferase(AST), and Creatinine. Also, the oxidative stress marker Malondialdehyde(MDA) and antioxidant markers Catalase and Superoxide-Dismutase(SOD) were measured. Finally; rabbits were slaughtered and histopathological investigations were performed for the ovary, small intestine, liver, and spleen. Our findings showed that; Nano-Spirulina improved the oxidative status, elevated the reproductive hormones, and protected the examined tissues from heat stress effects. Spirulina stimulated folliculogenesis earlier than control rabbits. It could be concluded that; Nano-Spirulina enhanced puberty in female rabbits during heat stress.