The invention discloses a sprayer based on a magnetorheological fluid. The sprayer comprises a shell, a nozzle assembly, a magnetic field generation device and an elastic chamber containing a magnetorheological fluid inside; a liquid inlet and liquid outlets are arranged at the shell; the elastic chamber is arranged inside the shell and a liquid circulation channel is formed between the elastic chamber and the shell; the liquid circulation channel separately communicates with the liquid inlet and the liquid outlets; the nozzle assembly is arranged on the shell and contains spraying nozzles which communicate with the liquid outlets; the magnetic field generation device is equipped with coils which are arranged inside the shell and a control assembly which is in electric connection with the coils; and the control assembly is used to control the coils for generation of different magnetic field intensity. The sprayer provided by the invention can realize continuous adjustment of liquid flow, so as to improve the atomization characteristic and increase the working efficiency of variable spraying.