The invention discloses a vehicle idle speed test method, which decides through the ACC signal of a vehicle, the signal of a vibrating sensor of a motor and the speed signal of a GPS module. When ACCsignal is on, the vibrating sensor detects the vehicle vibration continuously within some time; and the speed signal of the GPS module is zero; and the vehicle is idle. When ACC signal is off, or thevibrating sensor fails to detect the vibration signal of the motor or the speed signal of the GPS module is more than zero, the vehicle is off idle. Accordingly, the idle speed state is detected underthe off idle state, and the off idle state is detected under idle speed state. The time for the vehicle to get into the idle speed state and the time for the vehicle to exit the idle speed are recorded. The invention facilitates restraint of management units on behaviors of drivers according to the idle speed records to reduce the oil consumption and the current costs. The invention is applicablefor various types of vehicles, and has the characteristics of high detecting reliability, usableness, being convenient for popularization and so on.