Abstract: Abstract: Pisha sandstone is a kind of weakly cemented sandstone with loose structure and low diagenesis. In order to study the evolution of the growth and development of the pore structure of cement-solidified Pisha sandstone and its influence on compressive strength, the samples of cement-solidified Pisha sandstone with cement content of 4%, 7% and 10% were prepared, and their unconfined compressive strength and microscopic morphology were tested. The transverse relaxation time and pore characteristic parameters of samples with different curing ages were tested by nuclear magnetic resonance. According to the relationship between the transverse relaxation time and pore size, the pore radius of the three sets of patterns were converted and divided into four intervals: micro pores (0-0.1 μm), mesopores (>0.1-1 μm), macropores (>1-10 μm), and crack pores (>10 μm). The relationships between pore characteristic parameters and pore radius on strength of cement-solidified Pisha sandstone was analyzed by using the grey correlation entropy method, and the grey prediction model of pore structure and compressive strength was established. The results showed that the compressive strength of cement-solidified Pisha sandstone increased with curing age, and the hydrated gelling products ettringite (AFt) and hydrated calcium silicate (C-S-H) improved the internal pore structure of the sample through expansion filling and cementation. The transverse relaxation time spectrum of cement- solidified Pisha sandstone presented a "double peak" structure. As the curing age increased, the first peak tended to move to the left, but the peak signal amplitude was basically unchanged, the second peak was shifted to the direction of the medium and large apertures and the peak signal volume tended to decrease. After 28 days of hydration reaction, the bound fluid index increased from 63.17% to 64.30%, and the porosity decreased from 30.96% to 28.42%, the porosity and bound fluid index were negatively correlated as a whole. In the process of hydration reaction, the most probable aperture moved to the direction of small pore size, ranging from 67 nm to 47 nm. With the increase of cement content, the proportion of the most probable aperture gradually decreased from 1.976% to 1.821%, the proportion of pore size in the range of 0-0.1 μm increased first and then decreased, but the proportion of pore radius in the range of 0.1-10 μm showed the opposite trend. The bound fluid index and the proportion of the pore radius of 0-0.1 μm had the most significant influence on the compressive strength, the GM (1,3) grey model had the high prediction accuracy, and the relative errors between predictive values and test values ranged -10.46%-6.77%. This study can provide valuable information for the improvement and solidification of loose Pisha sandstone in engineering projects.