Hydrazine has a wide range of industrial applications, but it is also a toxic and explosive chemical substance, which brings potential risks to human health and environmental safety. Therefore, rapid and sensitive monitoring of hydrazine is of great importance in environmental sciences and biological systems. In this work, a new near-infrared (NIR) ratiometric fluorescent probe (Ac-HY) was designed to detect hydrazine under double excitation and emission mode. Ac-HY exhibited large stokes shift (130 nm), high selectivity and sensitivity to hydrazine detection. The applications of Ac-HY probe for detecting hydrazine in vapor and imaging hydrazine in lipid droplets and zebrafish. Therefore, Ac-HY can be used to monitor the distribution of exogenous hydrazine in vitro and in vivo.