Hybrid rice ‘F you 498’ was used to study the effects of planting patterns (mechanical transplanting and manual transplanting) and potassium application rates (0, 60, 120, 180, 240 kg/hm2) on leaf characteristic, dry matter accumulation and translocation, grain yield. The results showed that, compared to manual transplanting, SPAD values of flag leaf and top second leaf of mechanical transplanting were lower after heading stage, however they changed relatively steady. The leaf area index(LAI) of mechanical transplanting was higher than that of manual transplanting at full heading stage. However, the descend range of net photosynthetic rate of flag leaf during 10th day to 20th day after heading stage was greater in mechanical transplanting. Compared with the treatment of non potassium fertilizer, applying potassium fertilizer could stabilize SPAD value of flag leaf after heading stage and the net photosynthetic rate after full heading stage. LAI of mechanical transplanting and manual transplanting increased with the increase of potassium application rate at first, then showed a downward trend. The largest LAI of mechanical transplanting and manual transplanting was obtained in potassium application rates were 180 kg/hm2 and 120 kg/hm2, respectively. With the increase of potassium application rate, the dry matter weight at different stages increased at first and then decreased. The mechanical transplanting had more advantage than manual transplanting in dry matter accumulation before jointing stage while that was contrary after full heading stage. Moreover, too high or too low potassium application rate was not conducive to dry matter transportation of stem–sheath and leaf in the later period of rice. The yield of manual transplanting (12 517.1 kg/hm2) was 3.21% more than that of mechanical transplanting (12 128.3 kg/hm2) due to the more spikelets per panicle and the greater sink size (total spikelets). An appropriate K could effectively enhanced 1 000–grain weight and seed–set rate and yield of the rice with mechanical transplanting. Under this experimental condition, the effect of potassium fertilizer on yield of the rice with manual transplanting was not significant. The optimal K application rate is 120 kg/hm2 for the mechanical transplanting.