[Objective] The effects of super-absorbent polymers (SAPs) on physiological properties of cucumber roots and leaves under different drought conditions were studied in order to clarify the internal relationships between plant growth and soil water conditions with SAP applications. [Methods] A pot experiment with varying irrigation amounts was conducted to study the effects of SAPs on physiological properties of cucumber rhizosphere moisture, root morphology, leave chlorophyll fluorescence parameters, and stomatal characteristics were measured under three different water conditions. [Results] ① The growth of cucumber roots was significantly inhibited by the SAP treatments. Compared with the control, total root length, average root diameter, total root volume, root surface area, and root dry weight of SAP treatments were significantly reduced by 3.4%, 24.2%, 62.1%, 41.0%, and 51.6%, respectively, when soil water content was 70% (FC₂) and 55%(FC₃) of field capacity. ③ Effective photosynthetic efficiency (F_v'/F_m') and actual quantum yield 〔Y(Ⅱ)〕 with SAP treatments initially increased and then decreased with increasing drought stress, while non-photochemical quenching (NPQ) showed the opposite change. Especially with FC₂ and FC₃, the photochemical quenching (q_P) values of cucumber leaves were significantly reduced by 5.5% and 9.1%, respectively, compared with the control. ③ The effects of soil water on open stomata number, total stomatal ratio, and stomatal opening of cucumber leaves were greater than the effects of SAPs. [Conclusion] Soil water content was one of the important factors determining whether SAPs can alleviate drought stress of plants. When soil water content was 70% and 55% of field capacity, SAPs aggravated the negative effects of drought stress on cucumber root growth and chlorophyll fluorescence characteristics.