The invention discloses a method suitable for reinforcing a three-axis mixing pile in a peat land layer condition. The method comprises the following steps: positioning the center of a pile; supporting a three-axis mixing pile machine, wherein the center of a drill pipe of the three-axis mixing pile machine is aligned to the center of the pile; starting the three-axis mixing pile machine, whereinthe drill pipe sinks into the peat land layer from the ground to mix while spray slurry in the sinking process; lifting up the drill pipe to return when the slurry is sprayed and mixed to the bottom of the peat land layer, and spraying and mixing the slurry in the lift-up process; and carrying out circular sinking and lifting up for many times to finish drilling, wherein the slurry sprayed by thethree-axis mixing pile machine is prepared by pre-mixing cement, water, sodium chloride and gypsum powder in a certain proportion in advance. The reinforcing quality of the three-axial mixing pile inthe peat land layer is controlled effectively by means of methods of comprehensively applying and adjusting cement content, changing spraying and mixing number of times, employing additives and the like.