The realtime monitoring of gravel filling for immersed tunnel foundation is very important. Experiment is made on a samescale gravel filling model. A new kind of method for realtime monitoring of gravel filling for immersed tunnel foundation based on gravel filling pipe bottom pressure monitoring system and related analysis is developed; and the variation of gravel filling pipe bottom pressure under different construction conditions is studied. The study results show that: 1) The bottom pressure variation laws, wave shape and increases gradually, of gravel filling pipe No. 1 with different filling directions and same spacing are the same; the variation laws are related to formation and dissipation of gravel deposit. 2) The pressure threshold value of gravel deposit expansion can be determined according to the observation results. 3) The influence of bottom pressure of early gravel filling pipe on that of later gravel filling pipe is obvious, resulting in the larger and more complex variation of bottom pressure of later gravel filling pipe with different filling directions. The pressure of gravel deposit formed by later gravel filling is larger than that formed by early gravel filling.