Abstract: In this paper, ＂Similar Cycle＂ method is introduced and applied to predict the onset of solar cycle 24. Meanwhile, the smoothed monthly mean sunspot numbers of the last cycle descending phase are predicted. According to the characterestics of cycle 23, six cycles （9, 10, 11, 15, 17 and 20） are selected as the similar cycles of cycle 23 and was used to predict the beginning of cycle 24. The results are： （1） The beginning of cycle 24 will occur in the period from April to June, 2007. The length of cycle 23 may be 11.1 years. （2） The minimum smoothed monthly mean sunspot numbers is 7.1±2.6. Compared with other predictions, the onset time of cycle 24 in this paper is close to that of Ref.[11],
[12] and MSFC. From the discussion on the solar cycle prediction methods, ＂Similar cycle＂ is thought to be an effective method to the prediction of long-term solar cycle evolution. It could be used to predict the ending time of a solar cycle with a leading time of 3-4 years or more soon after the maximum.