The balance of the pension fund is the guarantee of stable operation of the system and the key point is the balance of the basic old-age insurance fund，especially the basic old-age insurance fund of workers. In this paper，we use two basic methods including minimum base and median base of contribution to estimate the balance of the basic pension insurance fund in Shanghai. It is found that the amount of accumulated funds in individual accounts is lower than the minimum amount of individual contribution in most years and there is a serious problem of empty account in individual accounts. But the contribution of migrant workers to the pension fund income is relatively large so that the overcapacity of the pension fund in Shanghai has been overcome and it comes large surplus. However，the old-age insurance system is a long-term insurance system so that we should not only focus on the immediate balance of the fund and ignore the more important long-term balance. The insured who will enter the pension system in Shanghai will reduce in the future，in contrast，the population of pensioners will increase. In addition，the pressure to pay the fund is still great in the long run. We believe that it’s necessary to control the growth of empty account which is common in individual accounts and to gradually reduce the previous empty account. It will be silly to leave the problem to the future，so we can try use the long-distance method to disperse the future pressure in the time interval.To deal with long-term balance of funds with early planning will be a good idea.