In this research, in order to describe milk production traits lactation Mahabadi goat breed, seven statistical functions were fitted using 1665 milk production traits records and 833 body weight records. The milk production traits were milk yield, fat percent, fat yield, protein percent, protein yield, lactose percent and SNF percent. These records have been recorded on 123 goats during years of 2012-2013. Based on results, there was not considerable difference in curve fitting of milk production and its composition yield among used functions. However, Ali and Schaeffer and Narushin-Takma functions in fat and SNF percentage, and inverse polynomial and Gompertz functions in protein and lactose percentage had higher goodness of fit in comparison with other function. Average daily milk production, days to peak production, milk production in peak, lactation period, and milk persistency were estimated 1 kg, 22 days, 1.22 kg, 120 days, and 5.59, respectively.