This study was an exploration into monitoring technology of summer corn canopy SPAD values. A small lysimeter was used in the experiment to monitor spectral reflectivity of summer corn and SPAD values of plant canopy, which provided the basis for investigation of the responsive relationship between canopy spectral information and SPAD values. From this relationship, the sensitive wave band and the optimum spectral index were determined for the SPAD values of the summer corn under investigation. The findings suggested that the canopy spectral reflectivity decreased with the increase of SPAD values in the visible light band, but increased with the increase of SPAD in the near infrared band. The band to which SPAD was most sensitive was 700 nm and 690 nm when monitoring the original spectrum and the first differential spectrum respectively and the correlations with SPAD values were -0.498 (p < 0.05)and -0.538 (p < 0.01). The multivariate stepwise regression analysis found an optimum band combination of 405 nm, 408 nm, and 700 nm. From 73 published spectral indices, five indices, i.e., (SDr-SDb)/(SDr+SDb), MCARI//OSAVI, TCARI/OSAVI, SDr/SDb, and MTCI, were chosen because they produced a higher correlation with SPAD values of summer corn canopy. Among the five indices, the most suitable index was found to be (SDr-SDb)/(SDr+SDb), and the correlation coefficient was as high as 0.697 (p < 0.01) in the whole growth period. A combinational regression model of SPAD, built from sensitive band, spectral index, and optimum band, produced the following simulation performances in descending order:optimum band combination, spectral index, original spectral reflectivity, and first differential spectrum. A quadratic polynomial model built from (SDr-SDb)/(SDr+SDb) index, and a combinational linear regression model built from 405 nm, 408 nm, and 700 nm bands, were recommended as suitable models for spectral monitoring of summer corn canopy SPAD values.