An in-vehicle protection system includes a signal input interface, a vehicle protection circuit, and a global navigation satellite system (GNSS) module. The signal input interface receives an indication signal indicative of a status of a vehicle. The vehicle protection circuit includes a first processing unit, a second processing unit, and a controller. The first and second processing units perform predetermined action in response to abnormality of a vehicle, and have different computing power. The controller outputs the indication signal to one of the first and second processing units according to an operational state of the in-vehicle protection system. The GNSS module obtains positioning information of the vehicle. After the second processing unit detects an abnormal status of the vehicle, the first processing unit sends at least one of the positioning information and vehicle alarm information indicative of the abnormal status through a communication network.