The diurnal variation of photosynthesis-related proteins were determined using proteomics from cassava (Manihot esculenta Crantz) ZM–QZ1 leaves at five time points, including 06:00, 11:00, 15:00, 19:00 and 24:00 in the whole day. The results showed that leaf net photosynthetic rate reached the highest at 15:00, followed by 11:00, and the minimum occurred at 24:00. A total of 42 differential expression proteins were found to change significantly (P<0.05) with larger than ?2.0 times variation intensity at four time points (11:00, 15:00, 19:00 and 24:00) compared to at 06:00 time point. All differential expression proteins were identified to involve in photosynthesis, carbohydrate and energy metabolism, chaperones, etc., and 54.8% of differential expression proteins were related to photosynthesis, carbohydrate and energy metabolism. In the study, the main proteins related to photosynthesis were included in ribulose–1, 5–bisphosphate carboxylase/oxygenase large subunit, rubisco subunit binding-protein alpha subunit, ribulose–1, 5–bisphosphate carboxylase/oxygenase activase and D1. It was indicated that the expression levels of these proteins were close related to the intensity of photosynthesis judging from the synchronous change of these protein expression levels and the net photosynthetic rate in the five time points.