The invention relates to the field of rocket engine casts, in particular to a high-precision burning rate test device applicable to high pressure. The high-precision burning rate test device comprisesa top cover, a combustion chamber, and a nozzle, wherein the top cover and a combustion chamber shell, and the nozzle and the combustion chamber shell are respectively connected by thread structures,the combustion chamber is composed of the combustion chamber shell, an inflaming retarding layer and a grain, the inflaming retarding layer is arranged on a front end face of the grain, the nozzle iscomposed of a nozzle shell, a thermal insulation sleeve and a throat liner, the nozzle shell and the thermal insulation sleeve are sealed by dynamic and static sealants of polyphenylene ether silicone rubber, and the throat liner and the thermal insulation sleeve are bonded by an HX98-1 adhesive. The nozzle shell, the top cover and the combustion chamber shell are all made of a 30CrMnSiA material. The connection structure of the high-precision burning rate test device provided by the invention adopts a threaded connection structure, which is convenient for disassembly and assembly, can be reused for a lot of times, and improves the efficiency; and the ignition method of the high-precision burning rate test device provided by the invention adopts a cartridge bag ignition method, which is convenient for installation and reduces the cost.