Recently, paper recycling has been significantly increased for several reasons such as environmental concerns and coast-saving. Ultrasound is used in the paper industry at various stages. Deinking has an important and determinant role in the recycling of newspapers. The aim of this study was to conduct the process of deinking in order to improve the optical properties of newspaper as a cellulosic material by using ultrasonic pretreatment combined with chemical method. The hydrogen peroxide, sodium hydroxide, sodium silicate, poly sorbent 80, and Diethylenetriaminepentaacetic acid were utilized for chemical deinking. Effect of important parameters of ultrasonic pretreatments such as ultrasonic bath temperature and sonication time on deinking efficiency was investigated by using response surface methodology based on central composite design. After chemical treatment of obtained recycled pulps, maximum and minimum efficiency of deinking for hand sheet papers with 60 gsm grammage according to standard T 205om-88 were calculated about 88 and 45% respectively. Surface and 3D curves were created to show the interactions of the independent variables with response one (deinking efficiency). Based on the ANOVA test, the quadratic model presented the best explanation of variables interaction. Ultrasonic pretreatments increased brightness and decreased opacity of obtained recycled newspaper compared to the control ones. According to the statistical analysis, the effect of each variable on deinking efficiency was significant and sonication time was introduced as the most effective factor. In addition, 47 ^oC ultrasonic bath temperature and 31 min sonication time were determined as the optimal conditions for maximum deinking efficiency (86.95%).