The invention discloses a pump pressure type grouting circulation device for a top-drive drilling machine. The device comprises a flow detection pup joint, an insertion sealing assembly and a piston type slurry flow stop valve assembly which are sequentially connected from top to bottom, wherein the flow detection pup joint is composed of a hollow tube and a plurality of sound wave flow meters, the insertion sealing assembly comprises an upper pressing ring, a sealing rubber tube, a lower pressing ring and a pressing cap which sequentially sleeve the outer side of a center tube from top to bottom, interference fit can be formed between the sealing rubber tube and a sleeve, the piston type slurry flow stop valve assembly comprises a piston, a piston spring and a piston sleeve which are sequentially arranged from inside to outside in a sleeved mode, and further comprises a pump pressure type slurry channel composed of a valve element spring support, a valve element and a flow stop valveseat which are arranged in the piston from bottom to top. The grouting circulation device has the characteristic of variable length, the piston can extend in the grouting process and extend into a casing pipe, the problem of slurry floating is effectively avoided, grouting can be carried out in the process of lowering the casing pipe, the grouting is carried out while the casing pipe is lowered, and the operation period is greatly shortened.