The magnetic field-driven evolution of chiral spin textures in a thin helimagnet nanodisk with varied size is investigated by means of Monte Carlo simulation. It is demonstrated that the complex spin texture may simply be regarded as the superposition of the edged state with the in-plane spin orientation perpendicular or parallel to the edge and the bulk state with features similar to two-dimensional chiral magnetic films. With the increase of the external field, the proportion of the parallel spins of the edge state increases, and the spin textures finally transfer into the edged magnetic vortex. The arrangement of skyrmions strongly depends on the disk size. In addition, the uniaxial anisotropy and dipolar coupling in certain ranges are able to stabilize a special magnetic vortex with the skyrmionic core, while the disk size is comparable to the wavelength of helix state.