Recent trends of the micro/nano heaters are miniaturization and high efficiency. It is found that convective heat loss increase significantly with miniaturization, which hinders achieving high efficiency. However, the research on micro/nano heater structure considering convective heat loss is insufficient. Therefore, in this research, new structure to improve the efficiency of micro/nano-heaters by reducing convective heat loss is studied. Solid conduction theory is applied to qualitatively expect convective heat loss reduction since the dominant mechanism of convective heat loss around microwire is by conduction of gas molecules. Optimized device is fabricated to validate the theory. Heat transfer coefficient of microwire array is measured at various ratio of gap and the mean free path. Experimental result shows the rapid decrease of the power consumption to reach the same temperature of microwire array with decreasing ratio of array gap and mean free path. Also it is experimentally confirmed that convective heat loss change follows the size effect theory of solid conduction. To my knowledge, this is the first time to propose micro-heater structure considering the convective heat shielding.