The invention provides a battery assembly offline detection platform multithreading time synchronization method. A battery assembly offline detection platform generates verification signals through hardware and provides the verification signals to a battery assembly, data acquired by the battery assembly is read through CAN communication, after the output/input data is compared, whether each function of the battery assembly reach the standard or not is judged. Synchronous operation of a signal generation thread and a CAN communication thread of the battery assembly offline detection platform is hard to achieve, data comparison errors are liable to occur, and the detection result is unqualified. Aiming at the above problem, the invention provides a time synchronization method. The time synchronization method comprises that 1. a main thread creates the signal generation thread and the CAN communication thread; 2. initial synchronization of the signal generation thread and the CAN communication thread is carried out; 3. the CAN communication thread carries out data sampling through a time warping method; and 4. the main thread compares data of the signal generation thread with data of the CAN communication thread, and the detection result is obtained.