The primordial non-Gaussianity induces scale-dependent bias of the Hi with respect to the underlying dark matter, which exhibits features on the very large scale of the 21-cm power spectrum potentially observable with Hi intensity mapping observations. We forecast the prospective constraints on the four fundamental shapes of primordial non-Gaussianity (local, equilateral, orthogonal, and enfolded), with the current and future Hi intensity mapping experiments, BINGO, FAST, and SKA-I. With the current configuration of the experiments and assumed one-year observation time, we find that the SKA-I will provide tighter constraints on the local shape of primoridal non-Gaussianity than Planck. The results are (σfNLlocal,σfNLequil,σfNLorth,σfNLenfold)SKA-I=(0.54,86,25,43), (σfNLlocal,σfNLequil,σfNLorth,σfNLenfold)BINGO=(17,100,128,164), (σfNLlocal,σfNLequil,σfNLorth,σfNLenfold)FAST=(9.5,44,75,94). If the lower frequency band of FAST can be used, the constraint on local-type primordial non-Gaussianity will be σfNL∼1.62 which is better than Planck. In addition, if the observation time for FAST could be extended to two years, the constraint on the equilateral shape of primordial non-Gaussianity would be improved to σfNL∼32. Similarly, if the observational time of SKA-I could be extended to two years, the constraint on local and orthogonal shapes could be improved to 0.43 and 20, respectively, achieving better constraints than Planck.