At present,the complicated rice production process makes the mechanized rice transplanting become the focus of agricultural production.The transplanting technique of potted seedlings is to move the seedlings to the paddy field by transplanting the soil.Its damage to the seedlings is less in the transplanting process,which is beneficial to the tiller and green of the seedlings.However,for the various rice planting mode in the two-season rice of southern China with abundant sunlight and rainwater,the transplanting machinery of the fixed row spacing can not fully meet the requirements.Therefore,the development of adjustable rice seedling transplanting machine will greatly reduce the cost of farmers caused by purchasing different machines for different row spacing.At the same time,this machine can improve the efficiency of rice production and meet the local policy of adapting measures to local conditions.To sum up,in order to promote the development of mechanized transplanting of rice in the double-season rice area of southern China and to improve the versatility and universality of rice transplanting machinery,it is urgent to develop a rice potted-seedling transplanter which can change the row spacing.Considering the current situation where the long-mat seedling transplanter and fixed row spacing are in the majority in China,combined with the characteristics of rice cropping area in south China,with existing fixed spacing rice transplanter as prototype,this paper proposes a overall design scheme about rice potted-seedling transplanter with variable row spacing through the improvement and innovation The main research contents are as follows:1)The design scheme of rice potted-seedling transplanter with variable row spacing was proposed.With existing wuling willow machine 2z-430 walking type rice transplanter as prototype,through the way of improvement and innovation in combination with a new mechanism of sending and taking seedling.Then the design scheme of horizontal sending mechanism and vertical sending mechanism were analyzed in detail.2)The mechanism of variable row spacing of a new pot seedling transplanter was studied.According to the present situation of different row spacing of early and late rice planting in double cropping rice area in southern China,combined with agronomic production requirements,a variable row spacing method was proposed,which only changed the position of funnel without changing the installation position of transplanting arm,and its working mechanism was studied.3)Modeling and simulation of seedling fetching mechanism were conducted.This paper innovatively designed a seedling fetching mechanism of rice seedling transplanting machine,and then used MATLAB to carry out mathematical modeling of the mechanism..Its rod length and various parameters were determined through MATLAB optimization toolbox.Three-dimensional modeling of the mechanism was carried out by using SolidWorks and simulation research on it was carried out by using Adams/view.The simulation results verified the rationality of its motion trajectory.4)Use Adams/view to design the CAM contour of the rice seedling picking mechanism.The movement rule of the CAM follower was determined by analyzing the variation of the speed of the rice picking mechanism in Adams/view.According to the given movement rule of the follower and the working speed of the rice picking mechanism,the CAM contour was designed by Adams/view and SolidWorks was imported for modeling.5)The prototype manufacture and performance test of variable row spacing rice potted-seedling transplanter were carried out.The designed mechanism and components were processed and assembled in accordance with the design parameters,and the indoor idling test was carried out to test the stable operation of the machine under no load.According to the standard of mechanical industry,the damage rate,leakage rate and turnover rate of clamping rice pot seedling transplanter were further tested,and the test results showed that the transplanter met the design requirements,met the agronomic requirements of variable row spacing of rice,and could satisfy the planting mode of double-season rice area in southern China.