Compared with the commercial silicon solar cells, the Dye-sensitized Solar Cells (DSSC) have attracted more attention in recent years because of their advantages of high energy conversion efficiency and low fabrication cost. The structure and basic principle of a DSSC is presented in brief. The key components of a DSSC and the factors which have influence on its photoelectric conversion efficiency are analyzed. A porous nanostructure TiO$_2$ layer is fabricated on a flexible Indium Tin Oxide (ITO) substrate by using a coating method. Finally, a flexible DSSC solar cell is formed by combining the porous nanostructure TiO2 layer with some corresponding dye and electrolyte. The test result shows that the solar cell has an open-circuit voltage higher than 100 mV and a short-circuit current greater than 1.2 mA.