A three-dimensional magnetic resonance imaging method, comprising: applying a slab selection gradient to a subject by a gradient output module; transmitting a radio frequency pulse to the subject by a RF excitation module concurrently with the slab selection gradient, wherein the radiofrequency pulse comprises a continuous frequency bandwidth thereby exciting a slab of a subject to produce magnetic resonance signals with the continuous frequency bandwidth; performing a spatial encoding gradient (102, 103, 106) across three dimensions by the gradient output module to encode the magnetic resonance signals, wherein an equivalent encoded field of view =FOV which along a selected acceleration direction is controlled by the spatial encoding gradient, and the equivalent encoded field of view of that direction is made shorter than that of a normal 3D MRI scan; applying a slab separation gradient G sep simultaneously along with one of the spatial encoding gradients G spen (102, 103, 106) by the gradient output module to produce separated encoded resonance signals so that aliased images along the selected acceleration direction can be completely separated in the final outcome image; and receiving the encoded magnetic resonance signals by a RF receiving module; and reconstructing the encoded magnetic resonance signals into 3D images by an imaging processing module, wherein the FOV is defined by the equation: FO V n = 1 Δ k n, wherein Δ k n = γG n Δ t or Δ k n = γt Δ G n, wherein n denotes either dimension in 3D space = X, Y or Z dimension, Δ k n denotes the step size of k-space along that dimension which is the product of gyromagnetic ratio γ, spatial encoding gradient strength G n, and time duration between each sampling point Δt, the same effect of Δkn can also be achieved by a fixed gradient duration t, and assigning the gradient strength step so that Δ k n =γ(Δ G n)t, wherein the equivalent encoded field of view along the selected acceleration direction is made shorter by an acceleration factor W, wherein W is expressed as following equation: W = th FO V accel, wherein th denotes the excited slab size, and FOV accel denotes the encoded field of view along the selected acceleration direction, wherein the encoded field of view along image separation direction FOV' n is expressed as following equation: FOV ′ n = M × FOV n, wherein M is greater than or equal to the acceleration factor W so that each cross section of the reconstructed 3D image space can accommodate multiple images which are separated by the separation gradient in one graph, wherein the separation gradient G sep is expressed as following equation:, G sep G spen ≧ FOV n FOV accel so that the aliased images with distance FOV accel can be completely separated in the final outcome image. applying a slab selection gradient to a subject by a gradient output module; transmitting a radio frequency pulse to the subject by a RF excitation module concurrently with the slab selection gradient, wherein the radiofrequency pulse comprises a continuous frequency bandwidth thereby exciting a slab of a subject to produce magnetic resonance signals with the continuous frequency bandwidth; performing a spatial encoding gradient (102, 103, 106) across three dimensions by the gradient output module to encode the magnetic resonance signals, wherein an equivalent encoded field of view =FOV which along a selected acceleration direction is controlled by the spatial encoding gradient, and the equivalent encoded field of view of that direction is made shorter than that of a normal 3D MRI scan; applying a slab separation gradient G sep simultaneously along with one of the spatial encoding gradients G spen (102, 103, 106) by the gradient output module to produce separated encoded resonance signals so that aliased images along the selected acceleration direction can be completely separated in the final outcome image; and receiving the encoded magnetic resonance signals by a RF receiving module; and reconstructing the encoded magnetic resonance signals into 3D images by an imaging processing module, wherein the FOV is defined by the equation: FO V n = 1 Δ k n, wherein Δ k n = γG n Δ t or Δ k n = γt Δ G n, wherein n denotes either dimension in 3D space = X, Y or Z dimension, Δ k n denotes the step size of k-space along that dimension which is the product of gyromagnetic ratio γ, spatial encoding gradient strength G n, and time duration between each sampling point Δt, the same effect of Δkn can also be achieved by a fixed gradient duration t, and assigning the gradient strength step so that Δ k n =γ(Δ G n)t, wherein the equivalent encoded field of view along the selected acceleration direction is made shorter by an acceleration factor W, wherein W is expressed as following equation: W = th FO V accel, wherein th denotes the excited slab size, and FOV accel denotes the encoded field of view along the selected acceleration direction, wherein the encoded field of view along image separation direction FOV' n is expressed as following equation: FOV ′ n = M × FOV n, wherein M is greater than or equal to the acceleration factor W so that each cross section of the reconstructed 3D image space can accommodate multiple images which are separated by the separation gradient in one graph, wherein the separation gradient G sep is expressed as following equation:, G sep G spen ≧ FOV n FOV accel so that the aliased images with distance FOV accel can be completely separated in the final outcome image.