The invention discloses a detection technology for phosphorus in livestock and poultry excrement. The detection technology comprises the steps of (1) taking four glass test tubes, respectively adding 0.26ml of to-be-detected excrement sample solution in the first and second tubes, respectively adding 0.26ml of distilled water in the third and fourth glass test tubes, then, respectively adding 0.21ml of 10mol/sulfuric acid in each test tube, placing the glass test tubes in a thermostatic chamber, and digesting for 1.5-2h at 145-150 DEG C; (2) taking out the glass test tubes when contents become yellow, cooling for 3min at natural temperature, adding one drop of 31% of hydrogen peroxide, further digesting for 60-70min, taking out, cooling at room temperature, and further adding 0.6ml of 4iiiol/L sodium hydroxide solution; and (3) heating for 15min in boiling water to decompose phosphoric acid, and further adding 2.6ml of phosphorous agent for executing colorimetric determination. Operation steps and the used devices and materials of the detection technology are very simple, and the accuracy of phosphorus content determined finally is relatively high, so that the detection technology is worthy of being popularized energetically.