Abstract: At present， planting the parental seedlings for hybrid rice seed production was carried out artificially， which had a lot of problems such as large labor intensity， low production efficiency， high cost， etc. A kind of rice transplanter was developed to plant the parental seedlings synchronously as two lines of paternal seedlings and ten lines of maternal seedlings. The machine was developed based on 2ZT9358 riding rice transplanter， according to the requirements of seed production of hybrid rice. The key structure parameters were determined， and the design of parental seedling transplanting mechanisms， the screw shaft of the boxtransferring mechanism and other key components were determined. Field test showed that the operating performance of the designed transplanter was pretty good.Its productivity was 0.35 hm2·h-1， the paternal and maternal damaged seedling rate were 2.7%， 2.4%， respectively， the floating seedling rate were 2.2%， 2.0%， respectively， the miss planting hill rate were 3.1%， 3.2%， respectively， the laid seedling hill rate were 2.5%， 2.1%， respectively， the percent of pass of planting depth were both 94%， and the percent of paternal pass of relative uniformity were 90.5%， 91.8%， respectively， which were all in line with the national standard for rice transplanter （GB/T 208642007）. In conclusion， the designed rice transplanter could meet the actual requirements for hybrid rice seed production.

Key words: hybrid rice, transplanting parental seedlings synchronously, modal analysis, field test, hybrid rice seed production