In this study, cultivated rice Shennong 265 and Liaoyan 16 were used to study the effects of weed rice competition on morphology and yield of rice. The results showed that the competition of rice had no significant effect on the plant height of Shennong 265 and Liaoyan 16. The competition of weed rice had less effect on the tiller number, leaf area index, and leaf number, length, and width, and stem length of Liaoyan 16 than Shennong 25. Weed rice competition reduced the tiller number of Shennong 265 and had a significant effect on the leaf area index, leaf number, length, leaf width, and stem length of cultivated rice Shennong 265. During the jointing period, heading period, grain filling period, when there were 6 and 12 weed rice plants per square meter, the leaf area index of Shennong 265 decreased by 6.47%, 23.79%; 15.33%, 36.00%; 24.77%, 40.43%; 43.31%, 41.95% compared to the control, respectively. Additionally, weed rice competition reduce the width of the second and third leaves from the top and increased the length of the second and third internodes of the stem in Shennong 265. When there were 6 and 12weed rice plants per square meter, the actual yield of Shennong 265 decreased by 25.90% and 49.77% compared to the control, respectively, and the decrease in panicle number was the main factor contributing to the yield reduction of Shennong 265. The yield of Liaoyan 16 was much less affected by the density of weed rice than that of Shennong 265. Cultivated rice varieties with strong tillering ability were better able to adapt to competition with weed rice.