In this work, we present the shock wave induced reversible phase transition from crystalline to semi-crystalline states of lithium sulfate monohydrate (Li2SO4•H2O) that has been evaluated by X-ray diffraction, Raman spectroscopic techniques and the observed reversible phase transition sequence is P21– P21– P21-disordered P21– P21– P21– P21 for the number of shock pulses of 0, 1, 2, 3, 4, 5 and 6, respectively. The obtained reversible phase transitions are due to the chemical disorder, orientational effect and rotational disorder of SO4 units induced in the title crystal. Materials of reversible phase transitions influenced by external stimuli are highly deserved for the applications of molecular switches and dielectric switches.