Abstract: Different mixtures of sunflower (Helianthus annuus) straw and whole corn maize (Zea mays) were used in a single factor experiment. The sensory evaluation, nutrient content and fermentation quality of all treatments were determined and analyzed to assess the best ratio of sunflower straw and whole corn maize for mixed silage. Sunflower straw and whole corn maize were mixed in the following proportions by weight: 0∶10, 4∶6, 5∶5, 6∶4, 7∶3, 8∶2, 9∶1 and 10∶0. Sunflower straw could be ensiled successfully although it was a composite herbage and the primary fermentation was heterolactic fermentation; After ensiling sunflower straw and whole corn maize in the proportion of four to six, the contents of DM (dry matter), CP (crude protein) and EE (ethanol extract)in the mixed silage was significantly higher than that in the sunflower straw silage while the contents of Ash (crude ash)、NDF (neutral detergent fiber)、ADF (acid detergent fiber)、Ca and P was much lower (P<0.01). The pH value of all the mixed groups of silage was lower than 4; LA (lactic acid content)/TA (total acid) and PA (propionic acid)/TA ratios in all the mixed groups of silage were improved compared with sunflower straw silage while that of AA/TA was reduced; There was no BA (butyric acid)/TA in any of the mixed groups of silage. Of all the mixed treatment groups, NH₃-N/TN (total N) was lower than that of the sunflower straw silage. It was concluded that sunflower straw and whole plant maize mix-ensiling improved the quality of sunflower straw silage.