Abstract: In order to ensure the service safety of hydraulic concrete structures at early age, the mechanical properties and meso-structure tests of self-compacting concrete（SCC） at early age are carried out, which has theoretical and practical significance for exploring the early-age strength development of rock filled concrete（RFC）. In this paper, the SCC specimens with dimensions of 100 mm×100 mm×100 mm were made, and the development pattern of cubic compressive strength of SCC at different ages（1, 3, 7, 14, 28 days） was investigated. The relationship between age and porosity, pore size distribution of SCC was analyzed. A mathematical model was constructed to investigate the relationship between compressive strength and microscopic parameters（porosity and T2 spectral area） under the influence of age. The results are as follows. The cubic compressive strength of SCC increased nonlinearly with age, and the main growth period was within the first 7 days. The area of the first peak gradually increased, while the areas of the second and third peaks decreased. The number of small pores（micropores） inside SCC increased gradually, and the number of medium and large pores decreased. The area of the first peak and the porosity of micropores were positively correlated with the cubic compressive strength of SCC and can better reflect the development of self-compacting concrete strength. The fractal dimension of micropores increases first and then decreases, and the fractal dimension of mesopores and macropores increases gradually. And the fractal dimension of macropores is obviously larger than that of mesopores and micropores. The proportion of micropores increased rapidly before 7 days, and the proportions of mesopores and macropores decreased significantly, and both mesopores and macropores transform into micropores. By 28 days, micropores accounted for more than 80% of the internal structure. In the early age stage, the fractal dimensions of micropores ranged from 0.189 to 0.865, the fractal dimensions of mesopores was between 2.881 and 2.977, and the fractal dimensions of macropores varied between 2.906 and 2.998. Overall, the fractal dimension of macropores was significantly larger than that of mesopores and micropores.