The conventional load flow methods like Newton-Raphson load flow (NRLF), Fast Decoupled load flow (FDLF) provide poor performance under critical conditions such as high R/X ratio, heavily loading condition etc. Exploiting the decoupling properties of power system, reliable fuzzy load flow is developed to overcome the limitations of the popular methods. Both power mismatch and summation of power mismatches are taken as two inputs for fuzzy logic controller. Considering magnitude of power mismatch and sign of power mismatch, new 25 fuzzy rules are created from two sets of inputs. The proposed Decoupled Fuzzy Load Flow (FDLF) is applied to IEEE 14 bus, IEEE 30 bus, IEEE 57 bus and IEEE 118 bus under stressed situations. The test results prove that the proposed algorithm provides better performance than the conventional methods under critical conditions.