A method and a device for controlling an inspiration trigger and a breathing machine. The control method comprises: detecting a parameter value in an air passage in an expiration process (S102)； judging whether the parameter value reaches an inspiration trigger value changing with the autonomous expiration cycle of a patient (S104)； and determining, according to a judgment result, whether to switch from expiration to inspiration (S106). Through the control method and device, the inspiration trigger can be conveniently controlled, thereby reducing ineffective inspiration work of the patient without incurring a false trigger.
