The increasing demand for vegetable products can be fulfilled by increasing productivity, which could be achieved through effective mechanization. However, compared to the harvesting and threshing machinery, the development in the transplanter machine sector is still limited. There is a lack of automated seedling transplanters which could transplant multiple seedlings crops, as most of the existing transplanters are designed to work at a single speed, which results in a single plant spacing not suitable for different crops. Therefore, this study tried to optimize the existing transplanter, which works at a single and relatively low speed, to work at multiple speeds corresponding to other commercial transplanters. Firstly, the existing planter unit's design features were extracted and designed in the commercial simulation software. The real trajectory of the planter was extracted from highspeed camera video and compared with the simulated result to ensure the accuracy of the design. Next, the planter design was simulated at a different working speed (150 - 350 mm/s) similar to commercial transplanters and extracted the working trajectories. The working trajectories were compared, and the speeds whose trajectories tend to meet the requirement for ideal trajectories were selected. The selected speeds were tested for the planter in the soil bin test experiment, and it found that the planter unit can be operated at the speed of 200mm/s, 250 mm/s and 300 mm/s with crank rotation of 30, 40 and 50 rpm. The selected speed combinations are similar to that of other commercially available transplanters, and the test bin result showed that the planting performance of the planters was within the permissible range