A series of polyether polyurethane (PU) gel electrolytes are prepared with polyethylene glycol (PEG) and isocyanate as monomers, and adding liquid electrolyte formulated by 1,4-butyrolactone (GBL), (C4H9) 4NI and I2. The structure of the polyurethane gel electrolyte is characterized by dynamic mechanical thermal analysis (DMTA), Fourier transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The results show that this type gel electrolyte has a good thermostability and amorphous structure. The influence of PEG molecular weight and isosyanate monomer on the conductivity of PU gel electrolyte is analyzed. It is found that the conductivity of PU gel electrolyte increases firstly and then decreases with the PEG molecular weight increasing. When the PEG molecular weight is 10000, the conductivity of the gel electrolyte reaches a maximum of 6.13 mS/cm. However, change of isocyanate monomer has almost no effect on the conductivity of the electrolyte. That may be related to the formed network of PU gel electrolyte by scanning electron microscope (SEM) characterization. The quasi-solid-state dye-sensitised solar cells (DSSCs) assembled with PU gel electrolyte prepared by different PEG molecular weight show different photovoltaic properties. A high photoelectric conversion efficiency of 4.29% is achieved at 100 mW/cm2 when PEG molecular weight is 10000.