The early age cracking of concrete is concerned with its thermal expansion properties, which is mainly reflected by the thermal expansion coefficient. Reasonably controlling the coefficient is an effective way of reducing cracks in the early age of concrete. While thermal expansion properties are related to the micro-pore texture characteristics of the concrete. Micro-pore textures of concretes of different mixing ratios and curing time were measured via mercury intrusion porosimetry (MIP), and the thermal expansion coefficient was determined by the comparator. The analysis of test results indicates the correlation between the parameters of micro-pore texture and thermal expansion properties, and also shows a highly positive correlation between the pore area and the thermal expansion coefficient. The results provide a solution for reducing the thermal expansion coefficient, thus controlling the early age cracking.