Grouting pressure control is an important step in curtain grouting, by the analysis on the grouting pressure, the process of grouting filling, diffusion and compaction in rock fissures can be distinguished to regulate the slurry concentration, control the grouting volume, and further more to control the water control effects in curtain grouting and the grouting construction cost to a large extent. According to a curtain grouting water control project in Zhaojiawan copper mine, analysis is made on the variation of grouting pressure during the process of grouting filling, diffusion and compaction in rock fissures, which can be the reference to the pressure control of grouting construction.