In this paper, rapeseed canopy spectra was collected, in periods of seeding, bolting, flowering, lush flowering and pod, to generate ratio spectral index (RSI) and normalized difference spectral index (NDSI). In order to acquire the best RSI and NDSI, the most sensitive bands were obtained by employing receiver operating characteristic (ROC) map with the combination of down sampling and fine sampling. For the direct plant and transplant the best values are as followed: the seeding period: RSI(458 nm, 511 nm) and NDSI(433 nm, 517 nm), the bolting period: RSI(997 nm, 501 nm) and NDSI(990 nm, 510 nm), the flowering period: RSI(1 235 nm, 1 180 nm) and NDSI(235 nm, 1 180 nm), the lush flowering period: RSI(478 nm, 396 nm) and NDSI(484 nm, 416 nm), and the pod period: RSI(1 073 nm, 1037 nm) and NDSI(1 092 nm, 1 024 nm), respectively. By using the two best RSI and NDSI as features and the nearest neighbor method as classifier, the results of the qualitative identification model show that the best discrimination effect comes from the flowering period, the corresponding Youden index is 0.941 7 and 0.945 0, respectively.