A vertical axis wind turbine includes a wind guide module installed at the periphery of a vane module for turning axially, and a magnetic field module and a coil module installed at the periphery of a turntable of the vane module for generating induced electromotive forces, such that when the vane module is rotated by the action of air current, the magnetic field module is driven to rotate a coil of the coil module generates an electric current by the magnetic induction of the magnetic element of the magnetic field module. In particular, the whole vertical axis power generator can guide and concentrate the surrounding air current at flaps of the vane module by the action of the wind guide module, so that the vane module is capable of starting an operation easily, providing a high operating performance, and featuring an easy manufacture.