The invention discloses a waterproof emergency system for a car. The waterproof emergency system comprises a chip, a preposed water sensor, an acoustic survey instrument, water sensor groups, hidden air bags and an exhaust system, wherein the water sensor group includes a front-area water sensor group, a middle-area water sensor group and a rear-area water sensor group; the water sensor includes a shell, a water outlet, a dustproof and waterproof mesh, an electromagnet and an end cover; the exhaust system includes a first telescopic exhaust pipe, a second telescopic exhaust pipe, a third telescopic exhaust pipe, a lifting screw rod and a motor. Through combined work of a plurality of groups of water sensors which are distributed on different positions, the device can automatically monitor a wading situation of the car, and can grade different wading degrees of the car by virtue of computer processing, and starts a proper emergency plan in time; by virtue of skillful control of a mechanical structure, the device can avoid an error influence of falling rain water or splashing accumulated water, prevents the water sensors from misjudging and guarantees the accuracy of monitoring information.