Abstract: A crucial factor for rice seedling cultivation which is applicable for mechanical transplanting, and obtaining high yield is to raise strong seedlings with right seedling age, while a qualified seedbed soil is the most basic and important requirement.A scientific trial was set up in Jiangxi agricultural university in 2010 to find out the proper seedbed soil source for mechanical-transplanting of double-cropping rice seedling raising, Tested soil included dry silt for rice, dry silt from vegetables field and dry silt from dryland, which were aired, smashed and screened carefully.2 rice varieties were used in this trial, one is Jinyou 299(hybride early for double-cropping rice), and the other one is Tianyou122 (hybrid late).Seeds were planted in carpet like plate, 100 grains each, and 3 applicants per treatment.Seedlings transplanted with TOYOPF455S walking transplanter, planted 8 row30 m in each plot.We evaluated afterwards the source effect of different soil on seedling quality, mechanical-transplanting quality and rice yield.According to seedling quality performance and yield result, it turned out that seedlings raised in seedbed soil from vegetables field performed the best for mechanical-transplanting of double cropping rice, followed by that of from rice soil.There were significant differences in seedling quality among different soil source treatments, which showed that dry silt for vegetables field >dry silt for rice>dry silt from dryland (of which ">"means better than) .The double-cropping rice seedlings grew in dry silt for vegetables field got strong root system, and its total root quantity was on average 13.95% and 4.16% more than that in other treatments.Stem diameter and dry matter for seedlings grew in vegetable soil also performed the best among treatments, whose stem diameter was on average 17.01% and 12.98% larger than that in other treatments, and dry matter weight of 100 plants was 17.0% and 6.99% more on average.Strong seedlings and high seedling survival rate was obtained in dry silt for vegetable field, which was on average 3.53% and 4.23% higher than that of in other two treatments.Also seedlings in vegetable soil, the total N and TSS content were relatively high, which made the seedlings have a good capability and anti-stress ability; total N content was 4.80% and 2.06% higher, while the TSS was 12.05% and 6.66% more than that of grew in rice soil and dryland soil.There were significant differences in mechanical transplanting quality among different seedbed soil source.Treatment with dry silt for vegetables got a high seedling survival rate while a low miss planting rate which leaded to enough transplanted basic seedlings.The miss planting rate was 3.50% and 2.50% lower than that of treated with rice soil and dryland soil.Seedlings had short turning green time after field mechanical transplanting, with enough basic seedlings and well population quality, so the basic seedling quantity was 10.98% and17.41% more than that of other treatments.There were difference in double-season yield and effective spikes among treatments with different seedbed soil sources.The effective spikes in dry silt from vegetables field was 8.02% and 12.18% higher and its actual yield was 5.4%, 7.10% more than that of in other treatments.There were no significant differences among treatments in grain/head, filled grain rate and 1000 grain weight.Different seedbed soil can affect yield of mechanical transplanted rice of double-cropping, because it has significant effects on numbers of effective spikes.In summary, soil from vegetables field is an ideal seedbed soil source for mechanical transplanting of double-cropping rice seedling cultivation in Jiangxi province , and it may also works in other area.