Update information. As sessile organisms, plants have to respond to rapid changes in numerous environmental factors, mainly the diurnal changes of light, temperature, and humidity. Maize is the world’s most grown crop, and as a C4 plant it exhibits high photosynthesis capacity and stress resistance than C3 plants. Revealing the physiological responses to diurnal changes and underlying regulatory mechanisms will be of great significance for guiding maize improvement. In this study, we collected maize leaf samples at nine timepoints during a single day/night cycle, representing dark, low light, fast changing light, high light, and heat conditions, and analyzed the proteome and phosphoproteome, quantifying 7424 proteins and 5361 phosphosites. We established a phosphoproteomic database, and identified new phosphosites, increasing the total maize phosphoproteome coverage by 8.5%. Kinase-substrate network analysis indicated that 998 potential substrates were phosphorylated by 20 activated kinases. Through analysis of significantly changed proteins in abundance and phosphorylation, we found that the response to a heat stimulus involves a change in the abundance of numerous proteins that are involved in processes such as the responses to heat, hydrogen peroxide, and protein folding. By contrast, diurnal changes in light intensity, especially high light and fast changing light, dramatically regulate the phosphorylation level of proteins associated with light signaling, chloroplast movement, photosynthesis, primary carbon metabolism, and transmembrane transport, and multisite phosphorylation may play vital roles in these processes. Overall, the database of dynamic protein abundance and phosphorylation we have generated provides a resource for the improvement of C4 crop plants.