The model test of gravel filling of a largescale inland river immersed tunnel is introduced in detail. The gravel filling effects of the model before gravel filling, during gravel filling and after gravel filling are evaluated under different construction conditions by impact imaging method and full wave field nondestructive detection method. The results of model test are analyzed. The gravel filling technologies and gravel filling effect of immersed tunnel foundation are evaluated. The site monitoring items and technologies of gravel filling of foundation of the largescale inland immersed tunnel are introduced. The gravel filling effect of foundation of the largescale inland immersed tunnel is analyzed based on site monitoring results of gravel filling, underwater detection and segment settlement. Some conclusions are drawn as follows: 1) The formation and development of gravel accretion disk can be detected by impact imaging method. 2) The segment settlement monitoring results show that the gravel filling effects of foundations from segment E1 to segment E6 are good.