The utility model discloses an on - -spot warning device of expressway construction operation, including the fixed plate, first recess has all been seted up to the both sides on fixed plate surface, the inside of first recess is provided with infra -red equipment, the top fixedly connected with warning light on fixed plate surface, the second recess has all been seted up to the bottom of fixed plate both sides, the inside fixedly connected with loudspeaker of second recess, which comprises a fixing plate and i, the axle center fixedly connected with of the department battery of fixed plate bottom, solar panel and battery electric connection, the battery respectively with infra -red equipment and warning light electric connection. The utility model discloses a set up the fixed plate, reach the effect of fixed infra -red equipment and loudspeaker, through infra -red equipment, reach the effect of measuring the car distance, through loudspeaker, reach warning driver's effect, when the certain distance, can be effectual remind the driver, make things convenient for people's use.