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In connection with the spin frustration, the phase transitions of hexagonal ABX3 compounds are experimentally studied. For the XY-like CsMnBr3, it is revealed that the phase transition belongs to a new universal class governed by Z2×S1 symmetry. It is also revealed that though the phase transition is well established, the ordered phase in this substance as well as the intermediate phases in the Ising-like CsCoCl3, CsCoBr3 and CsNiCl3 dynamically fluctuate in a time scale slightly longer than the observation time of neutron diffraction. Crucial effects of strong one-dimensionality of the substances are discussed.