Abstract: The simulation of flame spread over thin solid fuel undermicrogravity with narrow channel was analyzed with dimesion theory and validated experimentally by using flame spread picture recording. The resultshows that the qualitative simulation of microgravity combustion on groundcan be achieved with reducing the size of test section. The trends of theflame spread rate varying with flow velocity in vertical and horizontalnarrow channels are quite different. The natural convection in horizontalnarrow channel is effectively suppressed, while that in vertical channel isnot.