The invention discloses a method for adjusting maximum transmission power of a direct current transmission line of a sending end convertor station, and aims to solve the problem that the maximum transmission power of a direct current transmission line is lowered as leads of an alternative current power transmission line are arranged in a phase sequence. The method comprises the following steps: sequencing N loops of alternative power transmission lines connected with an alternative current bus of a convertor station, respectively establishing electromagnetic transient simulation calculation models, calculating transmission power of the direct current power transmission line when actual leads of each loop of power transmission line are arranged in the phase sequence, adjusting the lead phase sequence arrangement of each loop of power transmission line, and further calculating the transmission power of the direct current power transmission line of each loop of power transmission line, the transmission power of a first loop of power transmission line, the transmission power of a second loop of power transmission line,..., and the transmission power of an Nth loop of power transmission line after the lead phase sequence arrangement, till the calculated transmission power of the direct current power transmission lines is maximum. The invention provides a practical method for adjusting the maximum transmission power of the direct current transmission line of the sending end convertor station.