Aerospike is considered a relatively simple and effective technique to reduce drag for hypersonic vehicles. Aerospike reconstructs the flow field and reduces drag, as well as modifying the magnitude and distribution of the skin temperature, thus influencing the radiation signatures of the blunt body. To explore the impacts of diverse aerospike on infrared radiation over blunt body, this study focuses on aerospikes respectively equipped with conical, hemispherical, and flat-faced aerodisks. The aerodynamic force, thermal property, and infrared radiation of the blunt body affected by the aerospike with three typical aerodisks are numerically simulated. This study provides theoretical reference for the design of low signatures aerospike and the infrared detection of related targets.The Navier-Stokes equation was solved based on the Reynolds averaging method to obtain the flow field of the plume. The flow field parameters were computed through finite rate chemical reactions with seven components. The skin temperature was calculated based on the thin-wall approximation and the radiative equilibrium wall. By Planck's blackbody radiation law, the infrared radiation signatures of the blunt body considering the wall occlusion effect are predicted with the ray tracing method. Two representative cases (H=15 km and H=40 km) were selected to analyze the effect of the aerospike on the blunt body, including the aerodynamic force, thermal property, and infrared radiation signatures.The drag reduction efficiency of the aerospike at 40 km decreases by about 1%–7% compared to that at 15 km. The aerospike with flat-faced aerodisk maintains drag reduction efficiency above 50%, exceeding the other two structures by 5%-13% (Tab.4). The aerospike reduces the temperature near the nose of blunt body by 35%–50%, and the heat reduction effect on the downstream of the blunt body is not obvious. (Fig. 15). For the flat-faced aerodisk, the peak radiation intensities decrease by 25.3% and 39.4% at side viewing and front viewing observation angles respectively (Fig.16). The maximum in-band radiance suppression rate reaches 19.3%, which is 2%–16% higher than the other aerodisks (Tab.5-Tab.6).Aerodisk shape directly affects the aerodynamic force, thermal property, and infrared radiation signatures of the blunt body. The aerospike has the best thermal suppression effect in blunt nose. The aerospike with flat-faced aerodisk features high drag reduction efficiency and is less susceptible to environmental impacts. Among the three types of aerospike structures, only the aerospike with flat-faced aerodisk demonstrates a heat reduction effect behind the blunt nose. The infrared radiation suppression capability of the aerospike is more effective in the MWIR band than in the LWIR band at 15 km, while the reverse holds at 40 km. At different observation angles and in different bands, the aerospike with flat-faced aerodisk mainly suppresses infrared radiation intensity, while the other types of aerospike only show such suppression at the front-view observation angle.