Abstract: J. E. Savage has developed an algorithm of constructing Boolean function's ring-siim normal form (RSNF),which is based on disjunction normal form (DNF). In this paper the complexity of Savage's algorithm ≤ 2·3_n-2_n-1 is obtained (the upper bound can be achieved) and two direct algorithms of constructing BSNF are given. The complexities of the two direct algorithms are the same, being 3_n -2ⁿ.