An unmovable limiter without water cooling structure is designed for the HH70 device. The main components are the graphite tile assembly and the base. The graphite tile assembly is mounted on the base through the inner hexagon bolt and butterfly gasket. The transient heat transfer analysis and thermal stress analysis of HH70 unmovable limiter are carried out based on COMSOL multi-physics simulation software. The simulation results show that under the working conditions of the loading heat load of the unmovable limiter being 1 MW·m^‒2, 1.5 MW·m^‒2 and 2 MW·m^‒2, and its sustainable time being 19 seconds, 12 seconds and 9 seconds respectively the stress and temperature of the component materials are within the allowable range, which proves that the designed unmovable limiter meets the requirements of HH70 short pulse operation. Moreover, it provides a beneficial reference for the design of other high heat load components of the device.