The present invention relates to a method for on-line monitoring of the moisture change in a sea cucumber thawing process. The method includes the steps of: selecting several frozen sea cucumbers, and putting them into a nuclear magnetic cavity with a preset thawing temperature; acquiring nuclear magnetic resonance echo signals by CPMG pulse sequence method, and testing the T1 weighted imaging in the sea cucumber thawing process by means of magnetic resonance imaging SE sequence; conducting inverse analysis on sea cucumber sample echo attenuation curve data by SRIT algorithm and making corresponding charts, thus obtaining the moisture change condition of the thawing process under specific temperature. The method provided by the invention can simulate different temperature environments, achieves real time on-line monitoring of the moisture change in the thawing process of frozen ready-to-eat sea cucumber, and also can distinguish samples at different thawing stages.