Abstract: Abstract: For efficient use of rice straw feed resources, rice straw bale silage technique has been developed in some countries like Japan and Korea. In China, rice straw silage is used very little, and rice straw is usually used as poor quality feed because of loose outdoor stacking, which leads to lower nutrient composition and poor palatability. In recent years, rice straw bale silage is being emphasized with the development of animal husbandry, rice combines and round balers. But small and medium-sized steel-roll round balers are main round balers developed in China, and it is easy to result in blocking in the head-feed rice combine (applied widely in rice harvesting) when round baler bales the intact rice straw. When harvesting intact rice straw using domestic small and medium-sized steel-roll round balers, in order to eliminate the blocking problem and reduce the baling power consumption, a baling mechanism which combined steel rolls and side disk was designed (called roll-disk baling mechanism for short). Then, the baling process of the roll-disk baling mechanism was analyzed from the aspects of mechanical and power consumption characteristics. Through mechanical analysis, the friction resistance of rice straw in baling process could be reduced, and the advance movement of rice straw in baling process could be boosted with the side disk, which would be beneficial to boost the formation of rotating straw bale core (the key of forming straw bale). Through power consumption analysis and pre-experiment, major factors influencing the baling performance of the roll-disk baling mechanism was decided as follows: disk diameter > rotational speed of steel roll > feeding quantity > length-width ratio (the ratio of straw length to width of baling chamber). These factors were also selected as the experimental factors, the straw baling formation rate (the ratio of number of straw baling formation to total number of experiment) and baling power consumption were used as the evaluation indices, and 4-factor and 5-level orthogonal rotational combinatorial experiment was conducted with the experimental equipment of the roll-disk baling mechanism. By the above experiments, the regression model for formation rate of straw bales and the regression model for baling power consumption were obtained, which could be used to forecast the formation rate of straw bales and the baling power consumption for the steel-roll baler according to the results of variance analysis. Experimental results showed that major factors influencing baling formation rate could be ranked as round disk diameter, feeding quantity, steel roll rotational speed, and length-width ratio in a descending order, round disk diameter had the greatest influence among these factors, and bigger round disk diameter was beneficial to rapid formation of rotating straw bale core, which then helped to increase the baling formation rate; major factors influencing baling power consumption could be ranked as feeding quantity, rotational speed of steel roll, length-width ratio, and disk diameter in a descending order, and feeding quantity had the greatest influence among these factors. By this experiment, the optimized combination of parameters was decided as follows: Disk diameter of 380 mm, rotational speed of steel roll of 247 r/min, feeding quantity of 1.7 kg/s, and length-width ratio of 0.75. With the optimal combination of parameters, the straw baling formation rate and the baling power consumption were 100% and 62.7 kJ per bale respectively through the verification test of the roll-disk baling mechanism. Compared with the steel-roll round baler, there was no blocking and the baling power consumption reduced, and the roll-disk baling mechanism showed a better performance. These findings can provide theoretical and technical basis for optimization of structure and operation parameters of the roll-disk round baler.