| The study aims to investigate the effect of delayed harvesting on spring maize yield, 1000-grain weight, grain protein content, fat content, and starch content with five mulching treatments and seven treatments of harvesting time. The results showed that optimal harvest time significantly increased yield and grain quality of maize. With the delay of harvest time by 15 days, yield was increased by 10.19%～15.62%, 1000-grain weight by 10.19%～15.62%, grain protein content by 0.26%～1.29%, and protein yield by 117～230 kg·hm-2, and fat content by 0.05%～0.40%. Although starch content was reduced by 0.5%～4.9%, its yield was increased by 340～773 kg·hm-2. Extending harvest time to 15 days showed a significant increase in yield and grain quality of spring maize in Loess Plateau, but its effect varied with mulching patterns. |