We elaborate on the theoretical principle of estimating the size of accumulated couples under the new birth policy，involving four fertility release patterns and calculation procedures. Using these methods，we have estimated the scale of the accumulated couples and the numbers of new born second children. First，the number of accumulated couples would be at around 26.12 million in 2014 and vanish by 2040. Second，the proportion of accumulated couples to the couples of reproductive age would increase then decrease，and the peak proported would stand at around 7.9%. Third，the age structure of the accumulated women would be heavily at age 35 and below who have strong reproductive capacity. Fourth，the spatial distribution of fertility release would be uneven，with the urban area and the Eastern region having more accumulated couples and fertility release，and the provinces including Jianasu and Shangdong are the key provinces. Fifth，the number of fertility release would account for 30%-37% of the total accumulated children in first 5 years. Therefore，the new birth policy would have a smooth transition as long as we do the best to implement the new policy in the first five to ten years.