An analysis method for power transmission and power supply modes of a power grid is disclosed. The analysis method comprises the steps of establishing a simplified model of a power grid planning region adopting an interconnecting type partitioning structure based on the following conditional data: basic power supply condition data in the power grid planning region, site location of a high voltage level transformer as the power supply, and the configuration condition data of the high voltage level transformer; separately working out the short circuit current when the basic power supply is injected to the high voltage level transformer busbar and the power gird busbar, and the short circuit current when the high voltage level transformer busbar is injected to the power grid busbar according to the simplified model; and judging whether the power grid planning region selects the interconnecting type partitioning structure or an independent partitioning structure according to the magnitude relations between the short circuit currents and rated interrupting capacities of respective fuses. Based on certain preliminary information, the interconnecting type partitioning structure model of the power grid in the researched region is established, and whether the interconnecting type partitioning structure can be adopted or not is primarily evaluated and determined, so that the planning efficiency is improved, the workload is reduced, and infeasible schemes are avoided.