Abstract: Based on the close observation of compression experiments, the quantitative relations between macro-mechanical properties of soil and micro-parameters of particles are studied. By analyzing the movements of sand particles under monotonic loading, the association between the porosity ratio as macro-mechanical property of soil and the five micro-parameters of sand particles, including long axis L, short axis B, y-axis projection length, x, y coordinate of the centroid of particle is investigated, A quantified formula for the micro-parameters of particles and the porosity ratio is proposed. The quantization formula is modified in accordance with the test results of half mold compression tests. The porosity ratio e of sand sample top-surface circle center #1 observation point is slighter than that of #2 observation point. At 1/2 height of the sand sample, the porosity ratio e of centre point observation point #3 between axle wires of cutting ring and sand sample is slighter than that of observation point #4 of medial wall of cutting ring, and the e-p curve of observation points is plotted according to calculated results. The calculated porosity of all observation points demonstrates that the location of observation point has effects on grain movement and porosity ratio variation. By means of the experimental study on the association between the micro-mechanical properties of soil and the porosity ratio as well as the dispersoid micro-mechanics, a relevant method based on experiments for the association between the micro-mechanical and macro-mechanical properties of soil is proposed.