The invention discloses a magnetic resonance dynamic imaging method and a magnetic resonance dynamic imaging device. According to the magnetic resonance dynamic imaging method and the magnetic resonance dynamic imaging device, common data of a complete k space in period phases and respective unique data are subjected to image reconstruction separately, then a respective unique image of each periodphase is combined with the common image separately, so as to obtain a complete image in the period phases. When reconstructing the respective unique image of each period phase, image sparsity of different parts of the period phases is utilized for performing image reconstruction on the respective unique data of each period phase, thus an image with a high signal-to-noise ratio can be obtained bytaking the image sparsity as a constraint condition for conducting image reconstruction, and the high-quality respective unique image of each period phase can be reconstructed by adopting the magneticresonance dynamic imaging method provided by the invention even if an acceleration multiple of a magnetic resonance scanning speed is high. Therefore, compared with the prior art, the magnetic resonance dynamic imaging method and the magnetic resonance dynamic imaging device can increase the acceleration multiple of the magnetic resonance scanning speed on the premise of ensuring quality of reconstructed images.