Abstract: The harvest time is the key factor affecting seed quality of maize. The seeds of waxy maize selfcrossed from Huatiannuo 072 were harvested at 16， 20， 24， 28， 32， 36 and 40 d after pollination. Seed quality was determined when seeds were dried by nature to the similar moisture content. The results suggested that there were higher qualities when seeds were harvested during 32-36 d after pollination. Seeds harvested at 32 d after pollination had the highest standard germination ability and deepsowing germination ability. Furthermore， the electric conductivity was decreased to the minimum and was tending towards stability. Seeds harvested at 36 d after pollination had the highest thousandseed weight and germination ability at low temperature. Seeds harvested at 40 d after pollination had the strongest respiratory metabolism. The increased metabolism time（IMT）， oxygen metabolism rate（OMR）， relative germination time（RGT） was 878 h， 386%·h-1， 4256 h， respectively. To gain waxy maize seeds with high vigor， they should be suggested for harvest when electric conductivity is 41-43 μS·cm-1·g-1 or IMT， OMR， RGT is 1165-1178 h， 286-340 %·h-1， 5051-5446 h， respectively.

Key words: maize, seed quality, harvest time, oxygen sensor