We analyse the loading force transmissions for two kinds of loading structures directed at multistage octahedral cell of high pressure device, and build a mechanical relationship for high pressure producing efficiency. The relationship between cell pressure and hydraulic load is calibrated at room temperature for 14/8, 12/6 and 10/4 cell assemblies using the phase transitions of Bi, ZnTe, ZnS and GaAs under high pressure. Also we discuss qualitatively the influences of both mechanical configuration and hardness of last stage anvil on high pressure producing efficiency of octahedral cell. The experimental results show that both mechanical configuration and hardness of last stage anvil are key factors for affecting high pressure producing efficiency, what is more, the mechanical configuration is more important. The larger the geometry configuration of octahedral cell, the higher the high pressure producing efficiency is; high pressure producing efficiency of 6-8 type loading configuration is higher than that of 2-6-8 type loading configuration; when the pressure of octahedral cell approaches to Vickers hardness of last stage anvil, the harder the last stage anvil, the higher the high pressure producing efficiency and the higher cell pressure is.