One of the major causes of voltage instability is the reactive power limit of the system. Improving the system’s reactive power handling capacity via Flexible AC transmission System (FACTS) devices is a remedy for prevention of voltage instability and hence voltage collapse. In this paper, the effects of FACTS controllers, on static voltage collapse will be studied. Continuation power flow is used to evaluate the effects of these devices on system loadability. With the use of PSAT software, effects of these devices controllers on Maximum Loading Point are determined