The invention provides a new energy flexible direct current grid connection reliability estimation method. The method comprises the steps that 1) the output of a wind power plant unit is calculated; 2) the total output of wind power plant units in simulation time is calculated to determine the average output expectation of the wind power plant units, and a calculation result is taken as a wind power plant capacity factor C; 3) a reliability equivalent model of each MMC converter subsystem in a direct current transmission network is constructed; 4) a series-parallel network method is used to combine the reliability equivalent model of each MMC converter subsystem in the direct current transmission network to calculate the unavailability U of the combined direct current transmission network; and 5) the power delivery probability Pout of a wind power plant, the fault blocking power ESF of the combined direct current transmission network and the equivalent forced unavailability rate EUEQ of the combined direct current transmission network are calculated, and the reliability of the direct current transmission network of the wind power plant which accesses the direct current transmission network is estimated. The method can accurately estimate the reliability of the direct current transmission network of the grid-connected wind power plant.