To achieve high energy storage density and compact design of pulsed power source, a high power dual-spiral Blumlein pulse forming line (BPFL) using glycerol as energy storage medium is developed. The dual-spiral BPFL has a spiral middle cylinder and a spiral inner cylinder. Firstly, based on the consideration of insulation stability and energy storage density, the outer line and the inner line dimensions of the BPFL are calculated respectively. The output pulse width and line impedance are increased by adding the spiral on the middle cylinder and inner cylinder. Secondly, the transient field configuration in the BPFL is simulated by using the EM/circuit co-simulation software, and the transmission process of voltage wave in the BPFL is analyzed by the transient field distribution. The simulation results of the transmission delay in the outer line and the inner line are carried out. On this basis, the number of spiral turns in the middle cylinder and inner cylinder, and the inductance of the switch that affect the quality of the output waveform are analyzed. Finally, a 10 GW experimental platform based on dual-spiral BPFL is built according to the simulation optimization results. A pulse transformer is used to charge the BPFL to 600 kV. The device operated for 10 s under the frequency of 10 Hz. A quasi-square pulse with peak voltage of 712 kV and full width at half maximum (FWHM) of 136 ns was generated on a 50 Ω load. The ratio of single pulse energy to BPFL volume is 10.8 kJ/m³. And the peak-peak jitter of the pulse flat top is 3.8%, which has a high fitness with the simulation results.