The voltage collapse due to the failure of dynamic load restoration can suddenly occur before its static limitation, the estimation of this kind of voltage stability is still at the exploratory stage. In this thesis, fuzzy based voltage collapse alarm systems are proposed by considering both of static limitation and dynamic load restoration. The proposed alarm systems provide different degrees of alarm for the current operating state of power system and indicate that voltage collapse may occur, which is helpful for operators to take actions in advance. A lot of different voltage stability indices (VSIs) are studied, finally Line Stability Factor (LQP) is found to be an effective index to indicate the system transfer limitation when dynamic load is considered and it is selected as one of the inputs of the alarm systems. In order to represent the dynamic load characteristic, dQ/dt and dP/dt are proposed to be the other inputs of the alarm systems. In the previous alarm system, all buses of the power system are monitored. However, voltage collapse often starts at weak area, then proliferates to the overall system and makes the whole system breakdown. As a result, in this thesis, not all the buses but only critical areas that contains the proposed reactive power valley (RPV bus), weak lines and VCA-connection lines between different voltage control areas (VCAs) are monitored. After the theoretical analysis is finished, verifications are done through Matlab simulation. The feasibility and efficiency of the alarm system is verified on IEEE 39-Bus New England System with induction motor as dynamic load.