Abstract: A visual experimental investigation was carried out to research the characteristics of bubble evolution with natural convection in narrow space. The deionized water was used as working fluid. The experimental section was made by polycarbonate with narrow space size of 2 mm×10 mm×250 mm. To observe the bubble evolution from the bottom of experimental section, the heating section was made by FTO conductive glass. The characteristic curves of bubble growth were depicted with different heat fluxes. The results show that changes of the length and the width of bubbles conform exponential function during bubble growth. The aspect ratios of bubbles fluctuate nearby a constant value at the end of bubble growth. The rate of bubble growth is not linear with the imposed heat flux, which is affected by various parameters. Also, the characteristics of confined bubble coalescence were discussed in this paper.