Abstract: Hot-firing tests and numerical simulation were carried out on a 3-cell GH₂/GO₂ linear aerospike nozzle engine with round-to-rectangle primary nozzles. Test apparatus, structures and design parameters of the main parts concerned with the experimental engine were described. Data measured in the tests, experimental photograph and data analyses were presented. Aerospike nozzle flowfield was studied by numerical simulation and efficiency altitude characteristic of experimental aeropike nozzle engine was also predicted. The primary nozzle and inner layer of the combustion chamber were made of ablation-resistant W-Cu alloy and the aerospike ramp was made of steel. Detonation wave igniter was attempted to use on multi-cell aerospike nozzle and two short-duration hot-firing tests on the aerospike engine without generation cooling were executed successfully. The aerospike nozzle performance was obtained under two C_NPR which is the the ratio of combustion chamber pressure to ambient pressure. It is shown that good altitude compensation of thrust and high efficiency was yielded in the tests. Near C_NPR=50, efficiency is 92% to 93.5% and efficiency is 95% to 96% near C_NPR=350. The promising efficiency of more than 98% at design point can be expected.