Abstract: Pre-harvest sprouting causes huge economic losses to food production. The purpose of this study is to investigate the changes of phytohormone contents in hybrid rice during pre-harvest sprouting. HPLC methods were employed to analyze phytohormones content in this paper. Two different hybrid rice, including ‘Y Liangyou 1’ (hybrid parent is R9311×Y58S) and ‘II You 416’ (hybrid parents to R416×Ⅱ-32A), were used as the material. The results indicated that the seed germination rate of ‘Y Liangyou 1’ was much higher than ‘II You 416’. The endogenous hormone (IAA, GA1 ZR and ABA) content changes were investigated in pollination seed during15 d to 27 d. The results showed that the contents of endogenous hormone IAA and ZR, GA1 in ‘Y Liangyou 1’ is higher than that in ‘II You 416’, but ABA content is lesser than ‘II You 416’, and the ratio of GA1/ABA in ‘Y Liangyou 1’ Grain Endogenous is greater than ‘II You 416’. The content of phytohormones GA1, ABA and the ratio of GA1/ABA are most important reasons for pre-harvest sprouting during hybrid rice seed production process.