The invention discloses an ejection type safety warning sign for car, having a polyhedral structure for suppressing tumbling in a free state, capable of being restrained into tubular storage state by external force, and automatically releasing as polyhedral structure when external force disappears; polyhedral structure having warning marker on surface. A ejection system comprises: warning sign; launch tube having inner cavity for accommodating warning sign in tubular storage state; pressure tank communicated with end of launch tube; solenoid valve disposed between launch tube and pressure tank; controller connected to solenoid valve; launch tube having piston for pushing warning sign. When sudden situation occurs during driving, driver can press ejection button of warning sign while braking, so that warning sign can be ejected and stays near position of braking. Location of warning sign is at distance from position parking, eliminating take warning sign, promptly alerting rear car, reducing rear-end accidents.