A method for generating fluidized bed granular silicon , comprising the steps of: 1) generating seed using granular silicon raw material , the granular silicon raw material having a median diameter ,d50, the method including the following steps 2) and 3); 2) crushing said granular silicon by passing through a roll crusher apparatus , the roll crusher apparatus comprising at least one set of rollers , wherein the roller gap width between the sets of rollers is adjusted in such a way that the granular silicon particles which are larger in size than the roller gap width are crushed, and the granular silicon particles which are smaller in size than the roller gap width directly pass through the gap, thereby generating the seed , 3) and wherein the roller gap width x, the median diameter d 50 of granular silicon raw material and the median diameter D 50 of target seed satisfies the following relationship: 100μm < D 50 < d 50 < x < 2400μm, wherein the granular silicon particle size distribution range d p is 100μm to 2400μm; 4) introducing silicon source gas and fluidized gas into a fluidized bed reactor (FBR) within which the seed is loaded, where a thermal decomposition reaction is carried out continuously under 500°C to 1200°C reaction temperature, and granular silicon products are prepared from depositing silicon on the surface of the seeds ; 5) withdrawing a first portion of the granular silicon products prepared in step 1) from the FBR and sending for packaging as a final product ; 6) preparing a second portion of the granular silicon products and withdrawing them from the FBR and sending them to generate the granular silicon seed in steps 1) to 3), the seeds produced by said method being recycled back into the FBR, in order to maintain the number of particles constant within the fluidized bed reactor during step 4). 1) generating seed using granular silicon raw material , the granular silicon raw material having a median diameter ,d50, the method including the following steps 2) and 3); 2) crushing said granular silicon by passing through a roll crusher apparatus , the roll crusher apparatus comprising at least one set of rollers , wherein the roller gap width between the sets of rollers is adjusted in such a way that the granular silicon particles which are larger in size than the roller gap width are crushed, and the granular silicon particles which are smaller in size than the roller gap width directly pass through the gap, thereby generating the seed , 3) and wherein the roller gap width x, the median diameter d 50 of granular silicon raw material and the median diameter D 50 of target seed satisfies the following relationship: 100μm < D 50 < d 50 < x < 2400μm, wherein the granular silicon particle size distribution range d p is 100μm to 2400μm; 4) introducing silicon source gas and fluidized gas into a fluidized bed reactor (FBR) within which the seed is loaded, where a thermal decomposition reaction is carried out continuously under 500°C to 1200°C reaction temperature, and granular silicon products are prepared from depositing silicon on the surface of the seeds ; 5) withdrawing a first portion of the granular silicon products prepared in step 1) from the FBR and sending for packaging as a final product ; 6) preparing a second portion of the granular silicon products and withdrawing them from the FBR and sending them to generate the granular silicon seed in steps 1) to 3), the seeds produced by said method being recycled back into the FBR, in order to maintain the number of particles constant within the fluidized bed reactor during step 4). <EOS>