Two field experiments were conducted during late seasons of 2006-2007 at Baiyun Experimental Station of Guangdong Academy of Agricultural Sciences, Guangzhou, China. Tianyou 998, a hybrid rice, was arranged in split plot design experiments with straw mulching as main factor and N treatment as split factor with four replications. There were two levels of straw management and four N treatments. Straw mulching resulted in significant increase in grain yield at all N treatments. No significant differences were found in grain yield between three N treatments with the same total N input but different distribution among key growth stages. Path analysis showed that panicle number per m2 had the biggest direct effect on grain yield. Both maximum tiller number per m2 and productive tiller percentage were greater in straw mulching treatment compared to those in zerostraw mulching treatment. Straw mulching significantly improved dry matter production of rice plants. Leaf area index, chlorophyll content (SPAD value), and dry matter accumulation were significantly higher in straw mulching treatments at key growth stages. Grain yield was positively and significantly related with tiller number per plant, chlorophyll content of leaves, and dry matter production. Applying more N at early stage had no significant effect on grain yield, indicating that additional N at early stage was not necessary under straw mulching.