Greenhouse vegetable cultivation plays a crucial role in global vegetable supply. The planting year of vegetable greenhouses greatly affects vegetable yield and quality, whereas the study on vegetable quality using infrared spectroscopy is still unclear. Therefore, the mid-IR spectroscopy was used to detect how planting year of vegetable greenhouses (i.e., 1 year, 10 years, and 18 years) influenced cucumber quality by analyzing the specific peaks of cucumber fruits and leaves. In our study, the polysaccharides and protein components in cucumber fruits initially increased (the highest in 10 years) and subsequently decreased during the progression of the planting year. Raising planting years (i.e., 10 years and 18 years) increased lignin components of cucumber fruits (mainly in cucumber peel), which reduced the cucumber's taste. In addition, the ratio of organic components in cucumber can reflect cucumber quality under different greenhouse planting years. Polysaccharide/protein components and polysaccharide/lignin components in 18 years were significantly lower than those in 1 year and 10 years, implying that cucumbers of 1 year and 10 years had well-balanced carbohydrates and nutrients. Our finding suggests that short-term planting years (e.g., within 10 years) can improve cucumber quality, but long-term planting years inhibit cucumber quality. Therefore, comprehensively considering cucumber quality, we suggested that the planting year of the cucumber greenhouse should not be too long. Additionally, the organic components of cucumber leaves showed a similar trend to organic cucumber components across greenhouse planting years. Linear regression analysis demonstrated that cucumber fruits' protein and lignin components were positively associated with the protein and lignin components of cucumber leaves, which indicated that cucumber leaves might represent the nutrient and taste cucumber fruit. Overall, this study revealed the changes in organic cucumber components by mid-IR spectroscopy paralleled changed cucumber quality, providing scientific evidence for vegetable greenhouses management and improving vegetable quality.