Nitrogen is an essential nutrient element that affects the growth and development， yield and grain quality of maize （Zea mays L.）. To explore the key genes of maize endosperm in early development in response to low nitrogen stress treatment and reveal the physiological responses and molecular mechanism of maize endosperm against low nitrogen stress， the amino acids content and amino acid derivatives analysis， as well as transcriptome sequencing were performed on inbred line B73 kernel treated by low nitrogen and full nitrogen on six days after pollination. Physiological measurement showed that the contents of 10 amino acids or amino acid derivatives increased under low nitrogen stress， and the contents of threonine， β-amino-isobutyric acid， histidine， β-alanine， and lysine increased the most， with the increase ranged from 71.1% to 153.1%. The contents of other 21 amino acids or amino acid derivatives decreased， and the contents of ornithine， cystine， asparagine， phenylalanine， and α-aminobutyric acid decreased the most， with the decrease varied from 51.6% to 65.8%. Transcriptomic analysis showed that compared with sufficient nitrogen treatment， the 3，185 significantly up-regulated and 2，612 significantly down-regulated differentially expressed genes （DEGs） were identified in maize kernel under low nitrogen stress， respectively. In addition， a total of 12， 9， 20， 10， and 21 DEGs/differentially expressed transcription factors were detected in the nitrogen metabolism pathway， cyanoamino acid metabolism pathway， as well as AP2/ERF-ERF， bZIP， and WRKY transcription factor families， respectively. Therefore， these candidate genes may be important gene resources for maize endosperm response to low nitrogen stress， which may lay a foundation for the molecular mechanism of maize endosperm response to low nitrogen stress and develop low nitrogen tolerance maize varieties.