Ore pass enlargement construction method

The invention discloses an ore pass enlargement construction method. The method comprises the steps that firstly, like the traditional construction scheme, a small-diameter well is drilled; secondly, a part with a certain height H above the bottom of the well is selected and enlarged from top to bottom, wherein H is smaller than h, and h is equal to the time within which surrounding rock can keep stable when not supported or simply supported times the operation efficiency; thirdly, a part H to 2H away from the bottom of the well is selected and enlarged from top to bottom; fourthly, a part 2H to 3H away from the bottom of the well is selected and enlarged from top to bottom; the steps are repeated until the well is enlarged to the mouth of the well. The method has the advantages that the steps are simple, and the practicality is high.