Today One of the cases where in efficiency businesses including banks can be analyzed, discussed their size and scale of production, so as to check the size and scale 20 state and private banks were selected. The study period is 85-92 years. And data used are unbalanced panel. Then translog stochastic frontier production function was estimated .and scale efficiency changes was calculated. The key point extraction tools combined index for electronic components and using it as an input in the production function is a composite index. The results show that big government (Melli, Sepah, Keshvarzi, Maskan) to a large extent the technologically optimal production scale (most productive scale) away.Because of their scale efficiency changes, large and negative. On the other hand the big private banks (pasargad, parsian, eghtesadenovi) have been quite in technologically optimal production scale, In fact, their scale efficiency change is the lowest amount. Small government banks (postbank, Toseeh Taavon, sanat va maadan) similar large goverment banks are far from most productive scale, with the exception of the bank Toseah saderat of a good situation.small private banks (Sina, Sarmayeh, Saman, Day) as well as major private banks are the most productive technical scale Excluding Bank Day, which is partly attributed to most productive scale away.