A point-focusing diffractometer for the measurement of the small-angle X-ray scattering (SAXS) from molecular solutions has been constructed. This diffractometer consists of a double bent LiF monochromator whose focal length is 700 mm for Cu K_α radiation, a sample cell with 0.1 mm-thick mica windows, a bath circulator coupled with a cell holder, and a PSPC system. With this diffractometer, small-angle resolution of better than 0.42° is achieved. To evaluate the performance of the diffractometer, the SAXS on several pure liquids and aqueous solutions was measured. The results show that this diffractometer produces incident beams intense enough to measure SAXS on the solutions, making the collimation effect negligible simultaneously.