The invention belongs to the technical field of 
solid-liquid 
rocket engines, and aims to provide an internal spiral injection type 
solid-liquid engine grain aiming at the technical problem of non-uniform retreating of a burning surface in the length direction of a grain in the prior art. The grain comprises a 
metal framework body, and the 
metal framework body is of a hollow structure; and a plurality of sets of evenly-arranged hollow spiral structure blades are arranged in the 
metal framework body, a fuel medium is nested between every two adjacent sets of hollow blades, an air inlet 
pipe is arranged at the end of the 
metal framework body, and an 
oxidizing agent is evenly injected from the hollow blades in a spiral shape after passing through the air inlet 
pipe. The technical breakthrough that the 
oxidizing agent is evenly and spirally injected in the 
solid-liquid engine grain is achieved, meanwhile, the characteristic of rapid 
heat transfer of the metal blades is matched, the retreating speed of the fuel medium is effectively increased, meanwhile, uniform retreating of an internal burning face of a fuel channel is achieved, and therefore the 
engine power accurate adjusting difficulty is lowered; and the mechanical performance of the grain is greatly improved through the framework body made of the metal material, namely the working safety of an engine is improved.