Objective To explore the effect of a discharge preparation programme for elderly lung cancer patients based on the theory of dyadic illness management. Methods A total of 71 elderly lung cancer patients in department of oncology were selected, then they were randomized into a control group (n=35) and an intervention group (n=36). The control group was given routine nursing, while the intervention group received a discharge preparation programme based on the theory of dyadic illness management. The Readiness for Hospital Discharge Scale (RHDS), the Dyadic Coping Inventory (DCI) and the Comprehensive Needs Assessment Tool in Cancer for Caregivers (CNAT-C) were used to evaluate the intervention effect. Results After the intervention, the total score of RHDS in the patients and the total score of DCI in the patients and caregivers of the intervention group were significantly higher than those of the control group, while its total score of CNAT-C in the caregivers was significantly lower than that in the control group (P<0.05 for all). Conclusion Implementing the discharge preparation programme based on the theory of dyadic illness management for elderly lung cancer patients and their caregivers, is conducive to improving patients′ discharge readiness and support coping level, and meeting the comprehensive needs of caregivers.