AbstractA paper strength agent is an important type of chemical additive used in the papermaking industry. In this work some new paper strengthening agent samples were obtained by treating konjac glucomannan with hydrogen peroxide under acidic conditions, and their effects on paper properties were studied. Results showed that oxidized konjac glucomannan (OKG) can improve the paper properties effectively. When 1% oxidized glucomannan (oxidation 60 min, 35 °C) was added, the burst index, tensile index, and folding endurance were increased by 7.0%, 16.9%, and 102.3%, respectively, compared to the control. With increasing of oxidation time, the paper strength increased first and then decreased, reaching the maximum in 60 min. In addition, OKG can improve the properties of recycled paper more significantly. When the pH of paper making system was 7, the tensile index, burst index, and folding endurance of the recycled paper were increased by 22.2%, 19.9%, 59.9%, respectively, compared to the control. SEM analysis showed that paper strengthening agent resulted in a more contiguous junction between the fibers in paper.