Abstract: In view of the situation that Tienanyang main substation of Hangzhou Metro Line 1 phase III project can′t start operation on time as planned, three temporary support power supply schemes are proposed. The schemes are calculated and analyzed from three perspectives of system operation mode and reliability, cable voltage drop and economy. According to the calculation analysis results, an optimal temporary support power supply scheme is recommended, it can provide a referrable idea for support power supply schemes of metro industry medium-voltage ring network.