Abstarct: The end flaring of thin-walled tubes using single point incremental forming (SPIF) has the great importance in industries such as: aerospace, automotive and shipbuilding. This process, has been considered by researchers due to its high flexibility, no need to mold manufacturing and its application in the field of rapid prototyping. Since there has not been much research on the quality of the products made by this process, in this research, the experimental study and statistical analysis of variables affecting the dimensional accuracy and surface roughness of the formed samples were considered. Design of experiments was conducted baxsed on the response surface methodology (RSM). Then, baxsed on the experimental tests, the effect of input variables of SPIF process such as: tool diameter, vertical step size, angular step and lubricant type on the tube end diameter (TED) and roughness of internal and external surfaces of the stainless steel tube (AISI 304) was investigated. The measured output responses were statistically analyzed in Minitab software. The ANOVA results showed that the variables of tool diameter, vertical step size and the interactive effect of multiplication of tool diameter in the angular step have the most significant effect on the tube end diameter. In the following, the linear, quadratic and interactive effects of input variables on the roughness of internal and external surfaces of the tube end were extracted. Multi-objective optimization of responses was done using the desirability function. The optimum values of tool diameter, angular step, and vertical step size were determined to be 12 mm, 4 deg, and 0.43 mm, respectively, with the lubricant type be oil in order to achieve the maximum of TED and the minimum of surface roughness. By examining the thickness distribution of several specimens in the expanded area, it can be seen that by reducing the change percentage in the TED, more thinning is achieved at the tube end. Moreover, using spherical-head tools with greater diameters increases the end diameter of the expanded tube and reduces the spring-back.