The total alkaloid content in Pinellia ternate has also been measured out under 417 nm of wavelength according to principle of color method by acidic dye through extraction by chloroform and a variance analysis has been carried out. The result showed that there can obtain a curve with good linear relationship ( r =0.9989), high recovery rate (100.1%) and 2.3% of RSD and there also exists significant difference in total alkaloid content ( F=2.313,P<0.05 ) among different harvest periods, we can make such conclusions that this method is simple and quick, total alkaloids content reaches the highest point in the last ten days of August, but total average alkaloids output per plant is the highest in the period from middle and last ten day period of October to first tendency of November and the same is for optimum harvest period.