The invention discloses a method for detecting whitening 
efficacy of melothria heterophylla root extracts and relates to natural melothria heterophylla root extracts. The method comprises the following steps: (1) preparing a 
tyrosinase solution, an L-
tyrosine solution and a PBS (
phosphate buffer 
saline) solution as base solutions, then preparing four to-be-detected solutions, namely an 
arbutin solution, a supercritical CO2 extracted melothria heterophylla root extract solution, a water extracted melothria heterophylla root extract solution and an 
alcohol extracted melothria heterophylla root extract solution, quantitatively adding each base solution and one of the four to-be-detected solutions in four test tubes and shaking the solutions to be uniform; (2) heating the four test tubes in a water bath kettle, respectively determining the 
absorbance of each solution in each 
test tube under a wave length of 475nm and calculating the inhibition ratio of the to-be-detected solution with the concentration to 
tyrosinase; and (3) repeating the steps (1) and (2), determining the inhibition ratio of the other to-be-detected solutions to 
tyrosinase, determining the inhibition ratio of the other to-be-detected solutions with different concentrations to tyrosinase, and then according to the comparison of determination results, obtaining the whitening 
efficacy of each melothria heterophylla root extract and 
arbutin under the same concentration as well as the whitening 
efficacy of each melothria heterophylla root extract or 
arbutin under different concentrations.