In order to exploring the possibility of developing alginate oligosaccharides (AOS) as a novel plant growth regulator, using “Yuhua 9326” as experimental material, pot experiments were conducted to study the effects of spraying four kinds of foliar fertilization including potassium dihydrogen phosphate, urea, AOS, and composite biological agents (CBP) on photosynthetic characteristics, yield and nitrogen absorption and distribution of peanut using clear water as the control. The results showed that spraying four kinds of foliar fertilization improved net photosynthetic rate(Pn) of peanuts by 11.1% to 22.0%. The treatments of AOS and CBP (containing substances such as AOS, salicylic acid and others) had better application effects. Compared with the control with water, the side-bough length and branch numbers of these two treatments were increased by 13.1%, 11.4% and 15.9%, 50.9%, respectively, and the total dry weights were increased by 18.1% and 52.5%. The yield under the treatments of AOS and CBP were also significantly increased by 30.5% and 60.9%, respectively, which was mainly due to the increase in pods number per plant and hundred pods weight. Spraying CBP also promoted nitrogen absorption in peanuts, and raised its proportion in leaves and peanut kernels. In summary, the treatments of AOS or CBP improved peanut yield in our experiment, and the application effects of CBP treatment were the best, showing a wonderful foreground.