The invention discloses a microscopic crack dynamic in-situ characterization method, and relates to the technical field of crack in-situ detection. According to the method, a plurality of hardened
cement paste bodies are soaked in a
sulfate solution, the
porosity development trend of the hardened
cement paste bodies is obtained through a
nuclear magnetic resonance test and a mercury
injection test in the soaking process, a
test sample and a
test sample are prepared after soaking is finished, and the crack propagation length of the
test sample is measured through a
scanning electron microscope. According to the distance gradient between the sampling angle of the test sample and the exposed surface, space coordinates of crack
cracking are converted into a time process along the center axis of the test sample, a
delay microscope is established on the microscale, and the test sample is scanned by using X-
ray computed tomography equipment in a matched mode; a crack propagation
animation image is formed based on a crack form between adjacent X-
ray tomography slices, and a crack development process is obtained by continuously capturing high-resolution images, so that omission of
time information is avoided, and in-situ detection of microscopic cracks in a hardened
cement paste sample is realized.