Nowadays, nanotechnology is one of the most potential tools in the modern agriculture to improve productivity, adaptation to climate change and sustainable development. In this study, the effect of nanoscale zerovalent cobalt (NZVC) on the growth, photosynthetic parameters expressed by Fo (initial fluorescence), Fm (maximal fluorescence), Fv/Fm (maximal photochemical efficiency), ΦPSII (effective quantum yield of photosystem II), ETR (photosynthetic electron transport rate), Pn (net photosynthetic rate) and content of chlorophyll a and b at different stages in soybean leaves were investigated. The NZVC made from Vietnam and USA with different concentrations (0, 0.17 and 16.7 mg/kg seed) were used. It was found that when soybean seeds were treated with NZVC, the growth indices (such as the plant height, dry weights of stems and leaves and leaf area), photosynthetic parameters and chlorophyll a and b content were increased obviously compared with that of the control. These values had tended to gradually increase and reach maximum at fifth (V5) trifoliate stage, whereas they were significantly decreased at begin at flowering (R1) stage. The real productivity of the experimental formulas exceeded the control (5%), while the quality of grain was significant different among the plots. The zerovalent cobalt nanoparticle from Vietnam exhibited similar efficiency compared to those that came from USA. Our results indicated that photosynthesis was positively affected by NZVC, leading to the improved growth of soybean and therefore to improved productivity as a whole.