Abstract: Abstract: In 2012 and 2013, a field experiment was conducted to study the effects of magnetized water irrigation on rice growth, rice population structures, yield formation, and grain quality in China National Rice Research Institute located at Hangzhou City, Zhejiang Province, China. The Zhongzheyou 1 an indica type of hybrid rice and Yongyou 9 a japonica type of hybrid rice were used in the experiment. Split plot design was used with cultivars as the main plots and magnetized water irrigation (MTW) and a control (CK) as the sub-plots. The plots area was 35 m2 and repeated 3 times randomized complete block design. The magnetic instrument (Jinan Yishui Tech. Dev Co. Ltd.) was used in water magnetic treatment. The magnetic field in the instrument has an intensity of 0.2 Tesla, and the irrigation water passed throw the magnetic field at velocity of 1.5 m/s. From transplanting to harvesting the MTW plots were irrigated with the magnetic water, while the CK plots were irrigated with untreated water of same source. From transplanting to heading, the water levels of all plots were kept at the depth of 30-50 mm, while from heading to maturity the water levels were kept at the depth of 30-40 mm, then the plots were drained for 5 days before harvest. The results showed that the grain yield of MTW for Zhongzheyou 1 were 5.2% (2012) and 6.7% (2013) higher (P<0.05) than that of CK. and for Yongyou 9 were 8.8% (2012) and 9.3% (2013) higher (P<0.05) than that of CK. Compared with CK, The MTW increased the lower position tillers. During 14 days to 28 days after transplanting, the average tillers per hill of Zhongzheyou 1 and Yongyou 9 were increased significantly by 9.4% to 21.5% and 13.5% to 21.4%, respectively. Compared with CK, the effective panicle number of MTW for Zhongzheyou 1 were increased by 4.0% (2012) and 6.3% (2013) and Yongyou 9 were increased by 6.2% (2012) and 7.9% (2013). Compared with CK, the grain setting rate of MTW for Zhongzheyou 1 were increased by 3.9% (2012) and 5.3% (2013) and Yongyou 9 were increased by 8.7% (2012) and 5.0% (2013). All these differences were significant at 0.05 probability level. The increased effective panicle number and grain setting rate became dominant factors contributing to the high yield of MTW treated rice. Compared with CK, the chlorophyll value from SPAD chlorophyll meter for MTW of top 3 leaves increased by 2.4% to 7.1% for Zhongzheyou 1 and 2.6% to 7.8% for Yongyou 9. The dry matter accumulation per hectare significantly (P <0.05) increased by 5.7% to 18.8% (Zhongzheyou 1) and 6.2% to 16.5% (Yongyou 9) during booting and milk filling stage. Meanwhile, the MTW significantly (P < 0.05) improved the rice qualities. Compared with CK, the percentage of chalky grain of MTW for both Zhongzheyou 1 and Yongyou 9 were significantly (P<0.05) decreased by 13.3% and 12.0%, respectively. The chalkiness of MTW for Zhongzheyou 1 and Yongyou 9 were decreased by 11.4% (P<0.01) and 7.7% (P<0.05), respectively. The gel consistency of MTW for Zhongzheyou 1 and Yongyou 9 were increased (P<0.05) by 6.0 and 4.0 mm, respectively. The alkali spreading value of MTW for Zhongzheyou 1 and Yongyou 9 were increased (P < 0.05) by 4.3% and 4.8%, respectively. All of these indictors showed the improved rice qualities from MTW treatment. The results provided a scientific basis for the magnetic water application in the rice production.