Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) is a central regulator of metabolism and developmental transition in plant. Compound 991 is a well-known 5′-adenosine monophosphate activated protein kinase (AMPK) activator in mammals. SnRK1 and AMPK are highly conserved. However, whether 991 could also act as a SnRK1 activator is unknown. Adding 991 significantly increased the activity of SnRK1 in desalted extracts from germinating rice seeds in vitro. To determine whether 991 has biological activity in plant, rice seeds were treated with different concentrations of 991. Low concentration of 991 promoted rice seed germination, while high concentration of 991 inhibited rice germination. The effect of 991 on rice germination is similar to the effect of OsSnRK1a overexpression on germination. To explore whether 991 affects germination by specifically affecting SnRK1, the germination status of the snrk1a mutant and WT under 1 μM 991 treatment were compared. The snrk1a mutant exhibited insensitivity to 991. Through phosphoproteomic analysis, we found that the differential phosphopeptides caused by 991 treatments and overexpression of OsSnRK1a are largely overlapped. Phosphoproteomic analysis also revealed that SnRK1 might affect rice germination by regulating the phosphorylation levels of S285-PIP2;4, S1013-SOS1 and S110-ABI5. These results showed that 991 is a specific and workable SnRK1 activator in rice. The promotion and inhibition of 991 treatments on germination also exist in wheat seeds. 991 is expected to be used for exploring the function of SnRK1 in more detail and depth and chemical regulation of growth and development in crops.