A wireless scanner includes an optical scanning assembly which includes a housing, a light source circuit board, a reflective member and an image capture module. The housing has a bottom wall defining a window, a high end wall, a short end wall and two side walls. Two edges of the two side walls connecting with the top wall and the short end wall are defined as slopes. The light source circuit board is mounted to one of the two side walls and inclined upward and outward. The reflective member is mounted to the slopes and receives light from the light source circuit board to reflect it uniformly on the window. The image capture module is mounted to the high end wall for receiving light which is from an original in the window and reflected by the reflective member and then transmitting it to a Printed Circuit Board assembly.