We explore synchrotron radiations from a spiral moving electron under a uniform magnetic field along z-axis using Landau quantization. We found that this process generates a photon vortex with Bessel wave-function as the eigen-state of the z-component of the total angular momentum and the photon vortices with large angular momenta are generated by high-order harmonic radiations. We also calculate the decay widths and the energy spectra. Under strong magnetic fields as 10^13 G, which are found in astrophysical objects such as magnetars, photon vortices are predominantly generated.