The invention discloses a passive ignition mechanism for fire-fighting ejectors. The passive ignition mechanism comprises a handle main body (1) and a trigger (5) movably connected with the handle main body (1). A magneto (2) and a micro-switch (3) connected with the magneto (2) are arranged in the handle main body (1). The trigger (5) consists of lugs contacting the magneto (2). The passive ignition mechanism is featured with simple integral structure and small volume and is easy to realize by using the structure, and the security can be increased when the passive ignition mechanism is applied to the fire-fighting ejectors.