In Vietnam, the sludge from wastewater treatment systems in general and from the paper mill in particular is quite large. Particularly, an estimated 14,500 tons of sludge are generated annually from only the paper industry. However, at present mainly these sludge are applied forms of burial in landfills. It has caused difficulties for the construction of the landfill and waste of resources. Therefore, this study aims to investigate the possibility of using sludge as fertilizer to soil and crop improvement, and contribute to environmental protection. The results show that sludge from wastewater treatment systems of paper plant has high organic matter content (28.76% of organic C), rich in N (1.07%) and other nutrients such as P, Ca, Mg that should be used as fertilizer to improvement of soil fertility, and contribute increasing crop production. In this research, the sludge has a positive impact on soil properties, especially contributed significantly improve the amount of available nitrogen and soil humus. The high sludge applied generally produced greater biomass and crop yields. It is recommended that application of 10; 20 and 30 tons of sludge per ha have increased the pod yields of peanuts by 128; 144 and 155% compared to the control without application of sludge.