Tomato paper pot transplanting technology is one of the effective ways to obtain the high yield of tomato. Paper pot seedling automatic transplanting mechanization operation was generally done by the seedling taker which separated the pot seedling and put it into the planting apparatus. Then the pot seedling was implanted by the planting apparatus, the automatic transplanting was finished. In order to improve the efficiency of tomato paper transplanting, ensure the high speed and orderly separation of tomato seedling, solve the problem of high damage rate of tomato pot during transplanting with chain paper pot seedling, the angle adjustable tomato chain paper pot transplanting test bed was designed. Based on the analysis of working principle of the separating device and extraction device and the relationship between both of them, single tomato paper pot seedling was used as the research object. The operation process of tomato paper pot seedling completed from extraction device to separation device was analyzed and the mechanical model was established. In order to obtain the best working parameter combination of the test bed, the quadratic orthogonal rotation center combination test method was used to extract test factors such as the extraction speed, the speed ratio of the separating wheel to the leading wheel and the tilting angle of the separation wheel. The regression model between each factor and the evaluation index was established by taking the separation rate and the pot seedling damage rate as the evaluation indexes to carry out the test. The contribution rate of each factor to the evaluation index was analyzed. The results showed that the contribution rate of each factor to the seedling separation rate was in the order of the tilting angle of the separating wheel, the speed ratio of the separating wheel to the leading wheel, and the extraction speed. The contribution rate of each factor to the pot seedling damage rate was in the order of the ratio of the separating wheel to the leading wheel, the extraction speed and the tilting angle of the separating wheel. By optimizing the regression model, the optimum working parameters of the metering device were as follows: the separation rate achieved 90% and pot seedling damage rate was less than 5% when the extraction speed was 8~10m/min, the speed ratio was 2.5~4.6 and the tilting angle of the separation wheel was obtained as 18°. The research provided theoretical support and technical reference for the innovation, research and optimization of tomato chain paper pot transplanting machine.