Based on the actual runoff data in Han Jiamao hydrologic station of Hailiutu river from 1957 to 2010, the paper calculated base flow by BFI method and analyzed some characteristics such as interannual variability of runoff, nonuniform coefficient of annual distribution, degree of concentration, and variation range in different period.The results showed that: ① the base flow index is 0.864,witch mains that more than 80% river water come from groundwater. ② Between 1950s and 1960s, the annual runoff was higher; from 1970s to 1980s, the annual runoff was decreasing; in 1990s, the annual runoff had a continuous declination, and reached the minimum; However,there has been an increase since 2000. ③ Totally, the annual distribution of runoff was relatively even; but it was nonuniform from 1950s to 1960s; it tended to uniform from 1970s to 1990s; the annual distribution of runoff has been very nonuniform since 2000.