The invention discloses a turnover accumulated-water-proof bicycle cushion device. The turnover accumulated-water-proof bicycle cushion device comprises a cushion, a support connected with a bicycle main body and a connecting fixing unit. The cushion can rotate in a forward bending or backward leaning mode through the connecting fixing unit and is hinged to the top of the support in a positioned mode, and the rotating angle of the cushion is over 180 degrees. According to the turnover accumulated-water-proof bicycle cushion device, overturning of the bicycle cushion on the vertical surface by 180 degrees can be achieved, linear motion of a traditional bicycle cushion is developed into planar motion, and various requirements of all riders for the position of the bicycle cushion are met; and after cushion overturning, the disadvantageous effects such as soak and suncrack on the positive surface of the cushion, in particular to the genuine leather cushion in rainy days or hot summer days are reduced or even avoided. According to the turnover accumulated-water-proof bicycle cushion device, compared with the prior art, the comfort degree is worthy of cost by utilizing a same material, user selection is wide, the controllable freedom degree is higher, the convenient and practicable effects are achieved, operation is easy and reliable, and use is easy.