Voltage collapse appears in critical load power systems as a nonlinear phenomenon due to lack of reactive power. Voltage collapse causes black out problem in power system networks, therefore its problem should be prevented in order to operate of the systems continually. In this research, ANFIS-based composite controller (ANFIS-based CC-SVC) was proposed to solve this problem. The ANFIS-based was chosen because its computation complexity was more efficient than Mamdani fuzzy logic controller. Three-bus power systems were used to validate performance of proposed controller. An additional reactive load at j0.02 pu was forced to load bus in order to examine the effectiveness of the proposed controller. This controller was able to prevent voltage collapse and maintain bus voltage to setting value. Moreover, the settling time and increasing of the load voltage were achieved at time of 5.52 s and value of 0.0118 pu, respectively.