The invention relates to a method and a system for acquiring movement authority of block sections. The method comprises the following steps of acquiring a lateral receiving access length by taking a terminal protecting signal machine as a terminal point to determine coverage of a first block section, acquire a lateral receiving access stretching length and determine coverage of the second block section; and acquiring the lowest fixed limit speed value in a related access by taking the terminal protecting signal machine as a starting point, and adding the lowest fixed limit speed value as a target limit speed value of the second block section. By acquiring the movement authority of the two block sections on a lateral routine section, the lowest fixed limit speed of a train passing the lateral receiving access section is acquired, and the passing efficiency of a lateral train is improved.