The invention relates to a grouting device for conducting pressure grouting on a nuclear island reactor foundation bottom. The grouting device comprises grouting pipes arranged in a basic layer surface groove and is characterized by comprising a plurality of grouting pipe fixing supports fixed on two sides of the basic layer surface groove abreast in a linear mode at intervals. The grouting pipes penetrate through the insides of the plurality of grouting pipe fixing supports. The grouting device further comprises a plurality of grouting material level detecting devices fixed on the plurality of grouting pipe fixing supports. The invention further relates to a grouting system formed by the grouting device. The invention further relates to a grouting method for conducting the pressure grouting on the nuclear island reactor foundation bottom by using the grouting system. The grouting device, system and method is improved, and by using the grouting level detecting devices, the problem of density of the grouting material in a large-area grouting area is solved. Grouting speed of the grouting pipes in a grouting process can be observed, and grouting quality is prevented from being affected by air led in through the grouting material after the grouting pipes are pulled out of the liquid level.