Intercropping is a promising ecological intensification practice thanks to its improved crop yield and nutrient use efficiency compared with mono-cropping. However, there are constraints for achieving higher yields and efficiencies, and little is known about how to address such constraints. We conducted a field experiment to examine the impacts of ecological intensification measures (pollination services and cover crop addition) on productivity and nitrogen (N) surplus in wheat-maize/watermelon intercropping. During the watermelon growing season, we investigated pollination services using three treatments (full cover, semi-cover, no cover), and evaluated fruit set rate, yield and pollination service index. During the maize growing season, we evaluated the impact of a cover crop chicory (Cichorium intybus L.) on maize growth and soil residual inorganic N using three treatments (no cover crop, one and two cover crops). Compared with the full cover treatment, semi-cover and no cover treatments increased the fruit set rate of watermelon by 42.95% and 73.85%, and fruit yield by 10.84 Mg/ha and 11.48 Mg/ha, respectively. Pollination services accounted for 57.5% of relative watermelon yield. Compared with the control (no cover crops), planting cover crops increased the maize yield and N uptake. Planting cover crops reduced the apparent N surplus by 25.9-26.0 kg/ha compared to no cover crops. After the maize was harvested, inorganic N was largely distributed below the 60 cm soil depth. Providing pollination services and planting cover crops appears to be promising ecological intensification measures that improve productivity and decrease the N surplus of the intercropping system.